Soft Tissue Tumor Boot Camp

Transcription

1 General comments Soft Tissue Tumor Boot Camp Rajiv M. Patel, M.D. RCPA NZ ASM 2017 (11:00-12:30pm, Friday, ) More STT are initially sampled by core needle, FNA or other limited biopsy techniques to decrease patient morbidity Smaller specimens more challenging to interpret Sampling Problems with IHC A competent consultant is your friend Under diagnosis often poses greater risk than over diagnosis Misclassification is possible if several types of tumors share morphologic features When you hear hoof beats think of horses, not zebras Always rule out carcinoma, melanoma, lymphoma & mesothelioma before committing to a mesenchymal tumor diagnosis 2 General histologic approach Ensure lesion tissue present! Evaluate: 1. Growth pattern & architecture in conjunction with tumor cell cytology Look for clues to a specific diagnosis (e.g., Verocay bodies, lipoblasts) 2. Presence or absence of mitoses or necrosis 3. Use ancillary studies when necessary (e.g., IHC, molecular) If features are classic for a particular entity.go for it! If definitive diagnosis cannot be made determine if lesion is: 1. Benign or malignant 2. Low-grade, or high-grade malignant Regarding ancillary testing Make the diagnosis or put together a limited differential based on H&E appearance & pattern-based approach Universal IHC screening panel Keratin, S100, SMA, desmin, CD34 Check internal & external positive controls Look at entire slide! Know what constitutes a positive result for a given stain Stain looks positive in the cells of interest? In limited specimens negative staining may not reflect status of entire neoplasm Most relevant molecular tests can utilize FFPE tissue 3 4 Reporting Biopsy Clear diagnosis & grade if possible Descriptive comment with differential if the above not possible Resections Without adjuvant Tx If previously sampled review bx & confirm dx and adequacy of sampling Confirm any previous grading. Any higher grade areas present? Margin status With neoadjuvant % residual tumor viability Margin status 5 6 1

2 A Pattern-Based Approach 7 8 Pattern-based approach: What does it mean? Histomorphology-based Epithelioid Round cell Pleomorphic Spindle cell Myxoid Age-based Generally STT (particularly sarcomas) that arise in children, do not tend to afflict adults with the same frequency and vice versa (e.g.;, FHI in infants, or MFS in older adults); there are always exceptions Location-based Certain lesions tend to arise at particular anatomic sites (e.g., periungual SAF) Combination of the 3 highest diagnostic yield Morphology Evaluate all tissue on slide Size & depth Relation to overlying skin & fascia Borders (circumscription, encapsulation) Cellular differentiation Atypia Mitoses (abnormal forms?) 9 Growth Patterns Infiltrative vs. circumscribed Cellular Zonal Fascicular Palisading Multinodular Diffuse Stroma & Vasculature Myxoid Fibrotic/hyalinized Actinic damage Secondary elements Background vasculature (lobular, stag-horn) 2

3 Special Studies Special stains (PAS+/-) IHC Cytogenetics-FISH, RT-PCR EM (rarely used now) NGS (becoming more common) Other laboratory studies Another generality Pleomorphic vs. Monomorphic Sarcomas Pleomorphic sarcomas have complex karyotypes & multiple genetic abnormalities Monomorphic (translocation-associated) have a single molecular abnormality that is oncogenic Integrated Approach Examples of major histologic patterns Clinical Information Diagnosis Morphology Epithelioid Round cell Pleomorphic Monomorphic spindle cell Myxoid Special Studies Epithelioid pattern 3

4 11-year-old female with an ulcerated scalp mass Diagnosis? Cytokeratin AE1/3 Granuloma annulare? Necrobiosis lipoidica? Rheumatoid nodule? Dermatofibroma? Scar? Something else? CD34 IHC Epithelioid Neoplasms Antigen CA Melanoma/ EMPNST Lymphoma ES EAS ELMS CK + +/- melanoma, - EMPNST - + +/- - S-100/SOX SMA Desmin CD /- - CD conventional B & T-cell lymphoma, - most ALCL CD most conventional B & T-cell lymphoma, + ALCL CD31/ERG ALCL, anaplastic large cell lymphoma; EAS, epithelioid angiosarcoma; ES, epithelioid sarcoma; CA, carcinoma; CK, cytokeratin; EMPNST, epithelioid malignant peripheral nerve sheath tumor; ELMS, epithelioid leiomyosarcoma 4

5 Diagnosis? Epithelioid sarcoma EMA INI-1 Epithelioid Sarcoma (ES) Classic Epithelioid Sarcoma (CES) First described by Franz Enzinger in 1970 Most common in adolescents and young adults Two main variants: Classic Epithelioid Sarcoma (CES) Proximal Epithelioid Sarcoma (PES) Peak incidence in 2 nd decade Male preponderance Mainly affect hands, fingers and lower arm, followed by lower leg Presents as single or multiple firm nodules (usually <3cm in MD), +/- ulceration Mainly superficial with involvement of tendons, aponeuroses and dermis 5

6 Histology - CES Vaguely circumscribed cellular nodules Central necrosis, imparting a pseudogranulomatous appearance Epithelioid and spindle cells with eosinophilic cytoplasm and vesicular nuclei with small nucleoli Variable nuclear atypia Aggregates of chronic inflammatory cells at the periphery Hyalinised stroma Dystrophic calcification +/- metaplastic bone formation in 20% of cases Some cases have haemorrhage and pseudoangiomatous spaces Spindled variant resembles CDF 6

7 ES: Immunohistochemistry INI1 Co-expression of epithelial markers (CK & EMA) and vimentin CK expressed include both LMW and HMW cytokeratins 50-60% of cases CD34 +ve May be Factor XIIIa-positive mimicking DF Loss of INI1 (SMARCB1 protein) expression in >95% of cases 7

8 INI-1 (SMARCB1) Epithelioid Sarcoma-Proximal Type hsnf51/ini1/smarcb1/baf47 gene Tumor suppressor Loss of expression hallmark of pediatric rhabdoid tumors and atypical teratoid rhabdoid tumors of CNS Loss in >90% of epithelioid sarcomas, but not in almost all other sarcomas and carcinomas Genetics: complex rearrangements esp. 22q11, but SMARCB1 mutations not frequent, 8q gains frequently observed Proximal Epithelioid Sarcoma (PES) Affects older patients Involves deep soft tissues of trunk, pelvis, perineum & genital region, buttock & hip, head & neck Larger than superficial examples of CES Histology - PES Multinodular pattern Sheets of large cells with pleomorphic vesicular nuclei containing prominent nucleoli Rhabdoid morphology more common Focal necrosis (spotty necrosis) Rare cases of ES have myxoid stroma Some cases with hybrid features of both CES & PES described PES ES prognosis 40-80% recur and 35-50% metastasise CES recur in more proximal tissues as multiple nodules Not graded by the FNCLCC system Adverse prognostic factors: male sex, older age, proximal location, size >5cm, deep location, multifocality, mitoses, vascular invasion, lymph node involvement, necrosis and proximal type morphology 8

9 ES: Differential Diagnosis Granuloma annulare Necrobiotic granulomata (rheumatoid nodule, granuloma annulare) CK-, INI1 retained Cellular fibrous histiocytoma (CFH) Rule of thumb: Consider ES when contemplating CFH of distal extremity (ES may be FXIIIa+) CK-, INI1 retained Carcinoma (primary/metastatic) CD34-, INI1 retained Malignant rhabdoid tumour mostly in children, has diffuse morphology and show mutation of INI1 gene Epithelioid vascular tumours Myoepithelial lesions Express keratins carcinoma (can also show loss of INI1) Epithelioid Vascular Tumours Epithelioid haemangioma Epithelioid haemangioendothelioma Pseudomyogenic haemangioendothelioma (ES-like haemangioendothelioma) Epithelioid angiosarcoma 9

10 Epithelioid Haemangioma (EH) AKA angiolymphoid hyperplasia with eosinophilia and histiocytoid haemangioma Most widely documented in the skin and subcutis (head) Also described in bone, lymph nodes, lung, penis, eye, tongue, breast, arteries, colon, heart, spleen, and testis Skeleton probably 2 nd most common location Clinical: EH In the skin & superficial tissues presents as a solitary or cluster of small, pink to reddish-brown dome shaped nodules Adults commonly affected Patients with bone lesions have an average age of 35yrs EH of skin & subcutis is multifocal in up to 50% More than 18% of cases developing in the skeleton are polyostotic Simultaneous involvement of skin & bone is uncommon. Nielsen P et al (Am J Surg Path 2009) reported two out of 50 patients with discontinuous lesions of bone, skin, artery, and lymph nodes EH - Pathology Grossly, the tumours are solid, well circumscribed, reddishtan, haemorrhagic and lobulated Associated with a larger calibre, damaged thick-walled vessel in 60% of cases Vaguely lobular proliferation of vessels with epithelioid endothelial cells with abundant eosinophilic cytoplasm showing focal tombstone pattern +/- intracytoplasmic vacuoles Some vessels lack well defined lumina Inflammatory cell infiltrate including numerous eosinophils 10

11 CD31 Differential Diagnosis Kimura s disease Epithelioid haemangioendothelioma Epithelioid angiosarcoma EH vs. Kimura s Disease (KD) EH Slight female predominance No racial predilection Lymphadenopathy uncommon Peripheral eosinophilia in app. 20% of cases IgE levels normal Superficial, circumscribed, occasional lymphoid follicles, prominent vessels and non prominent stromal fibrosis KD Male predominance Asians more commonly affected Lymphadenopathy common Peripheral eosinophilia invariably present Increased IgE levels Deep seated, non circumscribed, vessels not prominent, abundant lymphoid follicles and prominent stromal fibrosis Epithelioid Haemangioendothelioma (EHE) Described by Weiss and Enzinger in 1982 Adults, M=F Subcutaneous soft tissues of extremities commonest site Other sites: skin, oral cavity, lung, liver, penis etc. Visceral EHE may exhibit a rather indolent clinical course Solitary, sometimes multifocal 11

12 EHE EHE EHE - Histology Multiple nodules Usually ass. with arterioles and venules Cords, trabeculae or solid nests/sheets of epithelioid cells Eosinophilic cytoplasm +/- cytoplasmic vacuoles/ lumina Myxohyaline to myxochondroid stroma Low grade nuclear features but subset of cases in the soft tissue (25-30%) have high nuclear grade, necrosis & frequent mitoses( malignant EHE ) EHE EHE CD31 AE1/AE3 Positive for: CD31 CD34 FLI1 ERG CK & EMA (40%) CD34 12

13 EHE: Molecular Cytogenetics >90% Epithelioid hemangioendotheliomas have t(1;3) (p36;q25) Fusion of WWTR1 and CAMTA1 WWTR1: transcriptional coactivator highly expressed in endothelial cells CAMTA1: DNA binding transcriptional regulatory protein usually expressed in brain Possible therapeutic target MR Tanas et al. Sci Transl Med. 2011;3:98ra82. EHE: Molecular Subset of EHE have TFE3 gene rearrangement WWTR1 - CAMTA1 negative +ve for TFE3 by IHC (in addition to endothelial markers) -ve for CK & HMB45 TFE3 gene rearrangement demonstrated by FISH EHE: Behavior Considered tumor of intermediate malignancy Frequent recurrence (10-15%) Lymph node and pulmonary metastasis (up to 30%) Overall mortality: 10-20% 5 year survival 50-85% 10 year survival 42-55% Treatment Wide local excision Amputation Lymph node dissection Malignant EHE 13

14 EHE Risk Stratification (Deyrup A et al. AJSP 2008) Criteria for malignancy (malignant EHE): >3cm in size >3 mitotic figures per 50HPF 59% disease specific survival in pts. with above characteristic vs. 100% DSS in pts. with tumours lacking the features Differential Diagnosis Depends on site involved: Epithelioid haemangioma Carcinoma (both primary & metastatic) Chondrosarcoma & ESMC Leiomyosarcoma (epithelioid LMS) Angiosarcoma (epithelioid AS) EHE: Key Points Any age but peak incidence 4 th -5 th decade F > M Myxohyaline matrix, nests, cords, chains, single file epithelioid cells, angiocentric growth, +/- intracytoplasmic vacuoles LMWCK 25% Inclusive of HG, LR 10-15%, Met 25%, mortality 10-15% Overall 5-year survival 73% WWTR1-CAMTA1 & YAP1-TFE3 specific fusions 14

15 Pseudomyogenic (epithelioid sarcoma-like) Hemangioendothelioma (PMHE) Rare entity originally described in 2003 Equally involves superficial or deep soft tissue Can present as ulcerated lesion Striking resemblance to ES (Am J Surg Pathol 27:48-57, 2003.) PMHE Very rare Some cases probably included in cases published as: Fibroma-like variant of epithelioid sarcoma (Mirra JM et al, Cancer 1992; 69: ) Spindle cell variant of epithelioid sarcoma Clinical: PMHE M>F (4:1) 2 nd -5 th decade mean 30yrs Multiple nodules Lower limbs> upper limbs >trunk >head Painful/non-painful Histopathology: PMHE Poorly circumscribed Infiltrative border Dermal, dermal + subcutis, dermal + subcutis + muscle Round, oval or spindled cells with vesicular nuclei and inconspicuous nucleoli Fascicles Focal myxoid stroma Ample eosinophilic cytoplasm rhabdomyoblastic appearance 15

16 Fascicles Poorly circumscribed Histopathology: PMHE Neutrophils frequently present Minimal nuclear pleomorphism Rare mitotic figures Necrosis is uncommon Some cases show intravascular invasion Subtle evidence of vascular differentiation consisting of focal intracytoplasmic lumen No overt vascular channels Neutrophils PMHE IHC: PMHE Hornick and Fletcher Am J Surg Pathol 35: , 2011 Positive for: AE1/AE3 ERG EMA FLI-1 CD31(50%) SMA (MNF116) Negative for: CD34 Desmin S100 INI1 expression retained 16

17 AE1/3 Fli-1 PMHE Balanced translocation t(7;19)(q22;q13) found as sole anomaly in 3 lesions of same pt.(trombetta et al Cancer Cytogenet 2011) Unbalanced t(7)t(7;19) in another case CD31 INI-1 Hornick and Fletcher Am J Surg Pathol 35: , 2011 Behavior: PMHE Epithelioid AS Relatively indolent Risk of local recurrence Regional metastasis vs. multifocal disease No distant metastasis No disease related deaths Angiosarcoma (AS) Conventional (idiopathic) Iatrogenic/Secondary: Lymphoedema assoc. Post radiation Thorotrast Foreign material PVC in hepatic AS In ass. with nerve sheath tumour Conventional AS Elderly pts Sun-damaged skin Head & neck M>F Histopathology: AS Solid sheets of atypical, mitotically active epithelioid cells Can be mostly spindled Vasoformation can be inconspicuous, usually seen at the periphery Can be easily mistaken for other tumours if index of suspicion low! Positive for vascular markers (CD31, ERG, CD34+/-) May be strongly keratin positive Subset show loss of INI1 17

18 AS IHC Epithelioid AS Use more than one endothelial marker CD31 not entirely specific, also expressed by histiocytes CD34 less sensitive than CD31 & not specific Fli-1 poor specificity; expressed by carcinomas, AFX/PDS, MM ERG sensitive & relatively specific May be strongly keratin positive Subset show loss of INI1 CD31 ERG ERG = ETS-related gene ETS family of transcription factor Expressed in normal endothelial cells Expressed by haemangiomas, lymphangiomas, almost all angiosarcomas, EHE and PMHE Also +ve in AML, subset of EWS + some prostatic adenocarcinoma Epithelioid angiosarcoma CD31 Clear Cell/Signet Ring Cell AS Other Morphological Variants of Epithelioid AS Foamy cell Granular cell Dermatopathol. 2014; 36; J. Cutan. Pathol. 2010; 37; J. Cutan. Pathol. 2012; 39; , 475 Am. J. Dermatopathol.2013; 35; Histopathology 2015, 66, Histopathology 2015, 66,

19 Mimics of epithelioid AS Myoepithelial Tumours of Skin & Soft Tissues Melanoma Epithelioid fibrous histiocytoma Relatively recently described & therefore not well recognised Encompasses tumours previously labelled as: Parachordoma Mixed tumours Chondroid syringoma Ectomesenchymal chondromyxoid tumour WHO currently considers the tumours to be part of a histological spectrum Most are benign Myoepithelial Tumours of Skin and Soft Tissues ~25% mixed tumours ~42% myoepitheliomas ~32% myoepithelial carcinoma or malignant mixed tumours Stout, 1959; Kilpatrick, 1997; Fernandez-Figueras, 1998; Michal 1999; Kutzner, 2001; Mentzel, 2003; Hornick, 2003; Flucke, 2011 Apocrine Mixed Tumor-Chondroid Syringoma Uncommon tumor composed of epithelial & mesenchymal elements Solitary, slow-growing nodule on the head & neck Middle-age to elderly Slight male predilection Well-circumscribed cm in diameter Benign but atypical & malignant variants described Lipomatous (apocrine) mixed tumor when fat is conspicuous 19

20 MNF116 p63 pcea Myoepithelial Tumours of Soft Tissues: Clinical Affects mainly adults (mean 38 years) ~20% of cases in patients younger than 20 yrs. No sex predilection Deep soft tissues of thigh > calf >upper limb >head & neck Slow growing painless mass Most <5cm in MD Most benign 20

21 Myoepithelial Tumours of Soft Tissues: Histopathology Often well circumscribed and lobulated or multinodular Cords, trabeculae and solid nests of epithelioid, ovoid and spindled cells with eosinophilic to clear cytoplasm Some hepatoid, plasmacytoid or vacuolated morphology Variably myxoid and chondromyxoid stroma Myoepithelial Tumours of Soft Tissues: Histopathology ~20% show ductal differentiation ~10% show cartilaginous and/or osseous differentiation ~5% show chordoma-like features Syncytial variant seen in skin Rare cases show squamous or fat metaplasia Cutaneous syncytial ME 21

22 Myoepithelioma: IHC Myoepithelioma: IHC AE1/3 SMA GFAP INI1 S100 SOX10 Myoepithelial Tumours of Soft Tissues: IHC Myoepithelial Tumours of Soft Tissues: IHC Negative for brachury INI1/SMARCB1 lost in ~20% of cases (most carcinomas) PLAG-1 +ve in most mixed tumours HMGA2 ve in ST mixed tumours GFAP +ve in ~ 50% Myoepithelial Tumours of Soft Tissues: Molecular EWSR1 gene rearrangement in ~40% of cases Fusion partners POU5F, PBX1, ZNF44, ATF1, PBX3, KLF17 FUS may substitute for EWSR1 PLAG1 gene rearrangement in most mixed tumours Brandal 2008; Brandal, 2009; Antonescu, 2010; Flucke, 2012; Agaram, 2014, Puls 2014; Huang

23 Myoepithelial Carcinoma of Soft Tissues Clinically aggressive recurrence/metastases in ~40% of cases Constitute a significant proportion of ST myoepithelial tumours occurring in children Criteria for malignancy not well defined: Nuclear atypia Prominent nucleoli Mitoses, necrosis or infiltrative pattern not considered reliable EWSR1 FISH Myoepithelial Carcinoma of Soft Tissues Myoepithelial Carcinoma Malignant myoepithelioma in skin malignant mixed tumor (very, very rare-aggressive) Morphologically & immunophenotypically similar to salivary gland counterparts Soft tissue cases predominate in pediatric population 75% of ST cases arise in limbs, typically subcutaneous Recur & metastasize 40-50% of cases to lungs, lymph nodes, bone & soft tissue EWSR1 translocation common outside salivary glands PLAG-1 in mixed tumors 23

24 Myoepithelial Carcinoma Myoepithelial Carcinoma Differential diagnosis Keratin SMA Extraskeletal myxoid chondrosarcoma Chondrosarcoma Chordoma Chondroid lipoma S-100 Ki-67 More ST with Epithelioid Variants Mammary myofibroblastoma Myxofibrosarcoma Rhabdomyosarcoma Clear cell sarcoma PEComa IMT Undifferentiated Pleomorphic Sarcoma with epithelioid morphology Epithelioid LMS Desmin SMA 24

25 Key points: Epithelioid pattern Epithelioid morphology not uncommon in soft tissue tumours (STT) Small proportion of STT have epithelioid morphology as the most distinctive and/or predominant feature (e.g., vascular lesions) STT with epithelioid morphology are a heterogeneous group of tumours, often with overlapping features Morphologically and immunohistochemically overlap with nonmesenchymal/epithelial tumours The resemblance of the tumours to each other and overlapping features with non-mesenchymal tumours present a diagnostic challenge Always rule out carcinoma, melanoma, lymphoma and melanoma before diagnosing and epithelioid mesenchymal neoplasm Key points: Epithelioid pattern A 5 stain screening panel including keratin, S100, SMA, desmin & CD34 is a good place to start. Order lots of unstained sections! Some of the most important mesenchymal tumors with this pattern include ES, epithelioid vascular tumors, epithelioid MPNST & myoepitheliomas 146 Round cell pattern 22-year-old male with a violaceous nodule of the right thigh 25

26 Abundant cleared-out cytoplasm secondary to glycogen deposition Small Round Blue Cell Tumor IHC AB SCCA MM ML Ewing- PNET RMS PDSS DRCT PANK + +/- - +/- Rare + + S /- Rare +/- - CD TdT Desmin - +/- - Rare CD /- + +/- + Rare AB, antibody; SCCA, small cell carcinoma; MM, melanoma; ML, lymphoma; PNET, primitive neuroectodermal tumor; RMS, rhabdomyosarcoma; PDSS, poorly differentiated synovial sarcoma; DRCT, desmoplastic small round cell tumor CD 99 Results of additional ancillary testing IHC negative for TdT, CD3, CD5, CD20, CD45, Mart-1, S-100, WT-1, CD57, panck, CK20, desmin, synaptophysin, chromogranin EWSR1 FISH positive Diagnosis? 26

27 Ewing sarcoma Cutaneous Ewing Sarcoma High-grade, small blue cell tumor affecting the long bones or vertebrae in children and young adults; male predominance ES and primitive neuroectodermal tumors (PNET)/peripheral neuroepithelioma are closely related tumors, considered as a single entity in the last WHO classification (Ewing Family of Tumors) 10-20% of cases are extraskeletal 5y survival: 68% for localized tumors, 39% for metastatic disease Primary cutaneous Ewing sarcoma Female predominance, later age (median 17 years), better outcome Might be due to early diagnosis and smaller tumor size Median tumor size 2.3 cm Predilection sites: lower limbs (38%), upper limbs (26%), head (20%) and trunk (16%) DD: Cutaneous metastases of osseous ES Metastasis in ca 10%, overall survival ca. 90% Primary cutaneous Ewing sarcoma: Histology Rather small, sharply circumscribed, basophilic, dermal or subcutaneous tumor Monomorphous, confluent lobules or sheets of densely packed small round blue cells with clear eosinophilic cytoplasm, fine chromatin, small nucleoli Rich vascularization, extensive capillary network (+/- visible) Mitotic activity usually not prominent Histopathologic features indistinguishable from ES/PNET of the bone Useful feature: high glycogen content of tumor cells, strong PAS+ Primary cutaneous Ewing sarcoma: IHC / molecular EWS (22q12) Break-apart probe IHC: 100% membranous CD99, 90% FLI-1 CD99 is highly sensitive but lacks specificity: should always be used as part of a panel of immunostains ERG specific for tumors with ERG rearrangement May express epithelial markers, 25% + with AE1/AE3 (diagnostic pitfall) Translocation EWSR1: EWSR1-FLI1 (>95%), EWSR1-ERG (2%), can have false negative (other rearrangements possible) Detected via FISH or RT-PCR in fixed, paraffin-embedded tissues t(11;22), t(21;22) EWS/PNET (FLI1/EWS, ERG/EWS) t(11;22), t(21;22) - DSRCT (WT-1/EWS, ERG/EWS) t(12;22) Clear Cell Sarcoma (ATF1/EWS) t(9;22) ES Myxoid Chondrosarcoma (CHN/EWS) t(16;22) Myxoid/Round Cell Liposarcoma (CHOP/EWS) 27

28 Ewing & Ewing-like family tumors translocations Table 1 CD99 Other notable Seminal references Gene fusions, chromosomal rkaryotype Anatomic location Morphology expression markers Ewing sarcoma EWSR1-FLI1 t(11;22)(q24;q12) Bone or soft tissues Ewing sarcoma or +++ FLI1 Delattre et al. (1994) or cutaneous so-called 'atypical Ewing sarcoma' EWSR1-ERG t(21;22)(q22;q12) +++ ERG Sorensen et al. (1994) EWSR1-ETV1 t(7;22)(p22;q12) Bone or soft tissues +++ NSE, S100, DES, EMA Jeon al. (1995) EWSR1-ETV4 t(7;22)(p21;q12) Extraosseous +++ Kaneko et al. (1996) EWSR1-FEV t(2;22)(q35;q12) Extraosseous +++ Peter et al. (1997) Round cell sarcoma with EWSR1 -non ETS rearrangement EWSR1-NFATC2 t(20;22)(q13;q12) Bone So-called 'atypical +++ None Szuhai et al. (2009) Ewing sarcoma' EWSR1-SP3 t(2;22)(q31;q12) Bone or soft tissues So-called 'atypical +++ NSE Wang et al. (2007) Ewing sarcoma' EWSR1-PATZ1 inv(22) in t(1;22) Chest wall PNET +++ DES, keratins Mastrangelo et al. (2000) EWSR1-SMARCA5 t(4;22)(q31;q12) Lumbar spine So-called 'atypical +++ NSE, Sumegi et al. (2011) Ewing sarcoma' Synaptophysi Round cell sarcoma with non EWSR1-ETS rearrangement FUS-ERG t(16;21)(p11;q22) Chest wall Ewing sarcoma +++ ERG, NSE Shing et al. (2003) FUS-FEV t(2;16)(q35;p11) Bone (clavicle) Ewing sarcoma +++ None Ng et al. (2007) Round cell sarcoma with CIC-DUX4 rearrangement CIC-DUX4 t(4;19)(q35;q13) Soft tissues URCS or so-called Weak focal WT1 Kawamura-Saito 'atypical Ewing et al. (2006) sarcoma' t(10;19)(q26;q13) ETV4 Round cell sarcoma with BCOR-CCNB3 rearrangement BCOR-CCNB3 inv(x)(p11) Bone URCS 50%+++ CCNB3 Pierron et al. (2012) DDx small round blue cell tumors Ewing sarcoma/pnet (bone/soft tissue or cutaneous) Neuroblastoma Alveolar rhabdomyosarcoma Lymphoblastic lymphoma Desmoplastic small round cell tumor (DSRCT) Metastatic pulmonary small cell carcinoma and cutaneous neuroendocrine carcinoma (Merkel cell carcinoma) Mesenchymal chondrosarcoma Small cell osteosarcoma Poorly differentiated synovial sarcoma Undifferentiated round cell sarcoma None (yet!) Non recurrent Variable URCS - Variable Fletcher (2008) Abbreviations: PNET, peripheral neuroectodermal tumor: URCS, undifferentiated round cell saroma, +++, strong membranous expression; -, no expression. Neuroblastoma Third most common pediatric tumor 96% before age 5, 25% are congenital Arise along sympathetic chain Up to 90% of patients have elevated urinary catecholamine metabolites CD99 -, neuroendocrine markers + No EWSR1 aberrations; MYCN amplification, deletion 1p Sheets of small round cells with little cytoplasm divided into small lobules by fibrovascular stroma Round dark nuclei Neuroblastoma Alveolar rhabdomyosarcoma Homer-Wright rosettes Rare aggressive neoplasm of children and young adults Deep soft tissues of extremities Overall 5yr survival <50% Does not respond well to traditional chemotherapy Conventional: Immunoreactivity for desmin or myogenin/myod1 should be present; 15% CD99 + t(1;13) or t(2;13) characteristic of alveolar rhabdomyosarcoma 28

29 Alveolar or solid growth pattern, variable rhabdomyoblastic differentiation Uniform small round blue cells Fibrovascular septa, discrete nests, center discohesive, multinucleated giant cells Alveolar rhabdomyosarcoma Myogenin Lymphoblastic lymphoma Usually children Aggressive; 2/3 curable with chemotherapy 85% B-cell, 10-20% T-cell IHC: B-cell markers, TdT (rarely negative), CD99 (membranous), CD179a/b+ Surface IgG, cytoplasmic IgM, CD15, CD30, CD45 - Lymphoblastic lymphoma Desmoplastic small round cell tumor (DSRCT) Malignant SRBCT with striking desmoplasia Mesothelial-lined spaces, rarely other locations Males years of age >75% DOD in <5yrs Sharply outlined islands of tumor cells separated by a desmoplastic stroma containing myofibroblasts and prominent vascularity DSRCT 29

30 Metastatic pulmonary small cell carcinoma and MCC DD particularly when patients >45 y and superficial Metastatic PSCC r/o if no pulmonary involvement clinic/rx Metastatic PSCC TTF1+ (- in Ewing) MCC has large cells, closely packed nuclei and little cytoplasm, frequently arranged in a trabecular pattern. MCC mainly in the dermis or subcutis, and 2/3 occur in patients >60 y MCC CK20+, CD99- Mesenchymal chondrosarcoma Bone or so3 4ssue, extraosseous location in ca. 20% Adolescents and young adults, but broad age range Biphasic pacern with islands of car4lage surrounded by sheet of small round cell (may spindle), hemangiopericytoma-like vascular pattern NSE, S-100, CD99 & SOX9 +, Fli-1 and ERG HEY1-NCOA2 fusion Biphasic pattern: islands of cartilage surrounded by sheet of small round cell, hemangiopericytoma-like vascular pattern Mesenchymal chondrosarcoma Mesenchymal chondrosarcoma Small cell osteosarcoma Very rare form of osteosarcoma Adolescents in metaphysis of long bones Diagnosis can be made if osteoid identified only, but may be only focally present in the tumor/missed in small biopsy specimens Most express neural markers (NSE, CD57), some CK, actin CD99 may be positive Uniform small round cells, osteoid, some spindled Small cell osteosarcoma 30

31 Poorly differentiated synovial sarcoma Malignant mesenchymal tumor with epithelial differentiation 10% soft tissue tumors Young adults, but any age Around the knee most common site, but any location High-grade sarcoma, significant potential for metastases and adverse outcome 5 yr. survival approximately 55% Biphasic, monophasic, poorly differentiated (round cell) Small cell osteosarcoma ES vs. alveolar rhabdomyosarcoma vs. poorly differentiated synovial sarcoma Ewing sarcoma ARMS PDSS Age yrs yrs yrs Site Extremi4es/trunk Extremi4es/trunk Extremi4es Histology Monotonous/small nucleoli Alveolar pacern/giant cells CD99 95% 25% 65% CK/EMA 30% 50% 90% Epithelial structures CD99 expression common, particularly in PD tumors TLE-1 is a robust marker for SS t(x;18) (p11.2;q11.2) (SYT- SS1/2) Synovial sarcoma Myogenin no >95% no Fli-1 80% no no TLE-1 no no >95% FISH EWSR1 break-apart FOXO1A break-apart SYT break-apart RT-PCR EWSR1-FLI1/ERG PAX3/PAX7-FOXO1A SYT-SSX1/2 Take home messages round cell pattern Wide differential, including epithelial, melanocytic, & hematopoetic neoplasms Rule these out before diagnosing a mesenchymal tumour Differential is often age dependent CD99, PanCK, S100, desmin, CD45 & TdT IHC narrows differential & informs use of additional ancillary tests Molecular testing for definitive classification increasingly important (e.g., CIC-DUX4,BCOR-CCNB3 sarcomas) 31

32 Pleomorphic pattern 80-year-old female with an ulcerated left upper cheek lesion 32

33 IHC panel for common pleomorphic cutaneous SCT Cytokeratin (wide spectrum, HMW, CK5/6) S-100 protein Melanocytic markers (HMB-45, Melan-A) SMA Desmin Endothelial markers (CD31, CD34,ERG) Sarcomatoid SCC Desmoplastic melanoma -/+ + -/+ - -/+ - AFX /+ - - Leiomyosarcoma -/+ -/ /- -/+ Angiosarcoma -/ S100 panck p63 Diagnosis? Atypical fibroxanthoma/ pleomorphic dermal sarcoma 33

34 Atypical fibroxanthoma (AFX) Histologically identical to malignant fibrous histiocytoma (MFH), but with largely benign behavior Almost always occurs in sun damaged skin Must be small (<1-1.5 cm), confined to dermis/subcutis, and completely visualized Diagnosis of exclusion No specific immunostains If does not meet criteria should be called pleomorphic dermal sarcoma (PDS) because higher risk of recurrence and mets Almost uniformly excellent prognosis following conservative tx; in one of largest series only 9/140 pts had recurrence; none had mets Atypical fibroxanthoma (AFX) Expansile dermal nodule on sun-damaged skin Less than 1.5 to 2 cm Confined to dermis or only minimal subcutaneous involvement Does not have extensive necrosis Bizarre cells with marked pleomorphism and easily identifiable mitotic figures Negative for S100, keratins, sma, desmin, CD34 & other vascular markers AFX AFX AFX AFX Atypical fibroxanthoma (AFX): DDx Sarcomatoid carcinoma: keratin positive; dysplasia in overlying epidermis Malignant melanoma: S100 positive; melanoma in situ Pleomorphic dermal sarcoma (AKA superficial undifferentiated pleomorphic sarcoma): larger than 2 cm, significant extension into subcutis or necrosis Spindle cell angiosarcoma (scalp): CD31 & ERG positive; areas of typical AS Leiomyosarcoma: perinuclear vacuoles, actin positive, desmin +/- Kaposi sarcoma: typically HIV +, HHV8 + 34

35 panck p63 Sarcomatoid SCC Desmoplastic melanoma S100 Spindle cell angiosarcoma Pilar LMS Typical AS at periph. of spindle cell AS 35

36 Pilar LMS KS KS KS HHV-8 DM vs. AFX vs. SSCC vs. AS vs. KS Clinical Pattern Morphology IHC Clue DM AFX SSCC AS LMS KS H&N H&N Variable Packeted, short fasc. Spindled S100+, CK- Sundamage, AJMH, Lymphs Storiform Pleomorphic S100-, CK-, SMA -/+, p63-/+ Sundamage, no epidermal component Storiform, fascicles Pleomorphic to spindled S100-, CK+, SMA-/+, p63+ AK or in-situ SCC Rapid onset Variable Typically HIV + Fascicles Fascicles Fascicles Spindled Spindled Spindled CD31 & ERG+ Areas of typical AS SMA, desmin+/- Perinuclear vacuoles HHV8+ HIV +, plasma cells 36

37 80-year-old male with rapidly growing cutaneous nodule on thorax 37

38 Pleomorphic lipoblast Pleomorphic spindle cell Diagnosis? Primary cutaneous pleomorphic liposacoma 38

39 Pleomorphic liposarcoma WHO definition: Pleomorphic high-grade sarcoma with a variable number of pleomorphic lipoblasts Uncommon form of liposarcoma that rarely occurs in the skin and subcutis, usually deep soft tissues Most common superficial variant of liposarcoma Aggressive 5% of liposarcomas, 20% pleomorphic sarcomas Extremities Elderly, M=F Overall mortality 50% Wide local excision +/- adjuvant chemotherapy Sites: retroperitoneum (7), scrotum (2), buttock (2), and abdominal cavity (1) 11/12 MDM2 amplification Sites: retroperitoneum (7), proximal lower extremity (3), chest wall (1), and neck (1) 12/12 MDM2 amplification 16 superficial (dermal and subcutaneous) 2/16 metastasized, 1 died Even superficial tumors may follow an aggressive course Multivariate analysis: age > 60 years, central location, tumor size, and mitotic rate predictors for an adverse outcome Cave adequate sampling (lipoblastic zones/ cellular zones) Results cutaneous /subcutaneous pleomorphic LS Differential: Pleomorphic liposarcoma Tumors located on the extremity (n=15), trunk (n=7), and head & neck (n=7) involved the dermis (n=4), dermis & subcutis (n=10), and subcutis (n=15) All were mitotically active high-grade sarcomas with either a pleomorphic spindled (n=24) or an epithelioid pattern (n=5) with variable extent of lipogenic differentiation MDM2 gene amplification was present in 3 of 26 cases Follow-up in 24 cases (median 48 mo): local recurrences (4/24) but no metastasis or death from disease. Conclusion: cutaneous and subcutaneous PLs, despite their high grade, have a much more favorable outcome compared with their deep-seated counterparts, most likely due to their small size and superficial location. The low incidence of MDM2 gene amplification indicates that most superficial PLs are unrelated to WDL/DL. Tumors with pleomorphic lipoblasts or pseudolipoblasts Other pleomorphic sarcomas that infiltrate fat (e.g., LMS, RMS, MPNST) Dedifferentiated liposarcoma or chondrosarcoma 39

40 Take home messages pleomorphic pattern Pleomorphic cutaneous soft tissue tumours: rule out sarcomatoid carcinoma, spindle cell/desmoplastic melanoma, spindle cell AS & LMS Pleomorphic sarcomas of soft tissue & bone: rule out component of a dedifferentiated liposarcoma (particularly retroperitoneal lesions) or chondrosarcoma, respectively Thoroughly sample to find identifiable low grade component or clues to specific dx (e.g. pleomorphic lipoblasts in PLS) Other sarcomas may be predominantly pleomorphic but also have identifiable low-grade areas (e.g., LMS, MPNST & RMS) Line of differentiation may only be discernable with IHC Monomorphic spindle cell pattern 55-year-old female with a 6cm neck mass

41 Diagnosis? Solitary fibrous tumor Solitary fibrous tumor Described by Klemprerer & Rabin 1931 Synonymous with hemangiopericytoma Not a tumor of pericytes Middle-aged adults First described in pleura, but wide anatomic distribution Subcutaneous (40%) Head & neck (10%) (show our paper) May present with hypoglycemia Produces insulin like growth factor I or II Small unpredictable risk of metastasis Pathologic features: Solitary fibrous tumor Well-circumscribed, 1-25cm (median 5-8 cm) Wide range of histologic features, ranging from cellular to fibrous with intermediate forms between the two ends of the spectrum Spindled to ovoid cells arranged in alternating hyper- & hypocellular areas in a patternless pattern, cellular variants more monomorphic Myxoid & microcystic change, nuclear palisading, chronic inflammation and mast cells common Staghorn branching vessels may be seen in all variants Predominantly myxoid SFT difficult to recognize Mitoses sparse & necrosis rare 41

42 Solitary Fibrous Tumour: IHC CD34 (95%) CD99 BCL2 EMA (33%) SMA (33%) Some cases may show focal S100, CK or desmin positivity STAT6 (translocation) STAT6 250 Add stat6 paper

43 Solitary fibrous tumor Criteria for malignancy Increased cellularity Mitotic activity (>4 mitoses/10hpf) Necrosis Some dedifferentiate Unpredictable clinical course, but most benign 5-10% recur or metastasize (lungs, bone liver) Vast majority that are aggressive are histologically malignant, but rarely benign SFT metastasize Complete excision with tumor-free margins Radiotherapy for local control of malignant examples should be considered Differential: SFT Synovial sarcoma Almost always CD34-, t(x;18) SYT-SSX, STAT6- MPNST Less circumscribed & less positive for CD34, arise from nerves LGFMS More uniform, less cellular and well circumscribed, MUC4+, STAT6- Desmoplastic mesothelioma (fibrous/pleural SFT) CK+, CD34 & STAT6-, cytologic atypia Deep fibrous histiocytoma (subcutaneous SFT) More prominent & uniform storiform growth pattern, secondary elements, CD34 & STAT6- Deep FH Deep DF 80-old-man with a nodule on the right dorsal foot, Rule out BCC

44 259 AE1/3 44

45 Synovial Sarcoma Malignant mesenchymal tumor with epithelial differentiation 10% STS Young adults, but any age Around the knee most common site, but any location High-grade sarcoma, significant potential for metastases and adverse outcome 5 yr survival approximately 55% Synovial Sarcoma Most litigated STT! Monophasic and Biphasic Biphasic pattern with epithelioid cell component forming glands, & a spindle cell component resembling fibrosarcoma AE1/3, CK7, CK19, EMA, TLE1+, focal S % t(x;18) SYT-SSX SS SS SS SS SS 45

46 Ancillary Studies TLE-1 Limited LMW & HMW cytokeratins and EMA TLE1 (not absolutely specific, but diffuse positivity a good bet) 30% S-100 protein expression CD34 negative (I have seen one exception) CD99 expression common, particularly in PD tumors t(x;18) (p11.2;q11.2) (SYT-SS1/2) TLE-1 TLE proteins (human homologues of Groucho) Transcriptional corepressors that inhibit Wnt signaling and other cell fate determination signals Established role in repressing differentiation Imperfectly specific Terry J, Saito T, Subramanian S, et al. Am J Surg Pathol Feb; 31(2):240-6 SYT (18q11) - Break Apart Probe Synovial sarcoma positive result Differential: Synovial sarcoma MPNST Lacks SYT/SSX translocation, arises from nerves Cellular schwannoma Strong and diffuse S100 Fibrosarcomatous DFSP Areas of classic DFSP Cellular blue nevi Melanocytic markers Solitary fibrous tumor CD34 & STAT6+ Small round blue cell tumors (poorly differentiated SS) 46

47 Cellular Blue Nevus Family Present in childhood to middle age Buttock, sacroccygeal region most common, followed by scalp, face, dorsal hands and feet Heavily pigmented lesions, often mistaken for melanoma clinically Amelanotic BN, flesh colored papules Benign CBN CBN CBN S-100 CBN HMB45 DFSP 47

48 Fibrosarcomatous DFSP Fibrosarcomatous DFSP Sarcomatous foci should constitute at least 5-10% of tumor Fascicular rather than storiform growth Increased mitotic rate (7-15 mits/10hpf) Significance is unclear Fibrosarcomatous DFSP: fascicular growth Fibrosarcomatous DFSP: increased mitoses MPNST MPNST

49 MPNST 289 PDSS PDSS PDSS Take home messages monomorphic spindle cell pattern Highly cellular mesechymal spindle cell tumors with fascicular growth patterns not uncommonly encountered Most common ddx: MPNST, cellular schwannoma, synovial sarcoma, SFT & fibrosarcomatous DFSP Combining light microscopy & IHC a specific line of differentiation can usually be detected In difficult cases molecular studies may be needed to differentiate translocation-associated monomorphic spindle cell neoplasms for morphologic mimics Myxoid pattern 49

50 Myxoid SST: Key features to evaluate Cellularity Extremely low= myxoma, relatively high= fasciitis Arrangement of cells with respect to one another Little cell-cell contact= MLS, touching= ESMC Nuclear pleomorphism Absent= intramuscular myxoma, high degree of atypia= MFS Underlying vasculature Low vascularity= intramuscular myxoma, intricate vasculature= MLS & MFS (Alcian blue ph 2.5) evaluation of myxoid stroma (rarely) Hyaluronic acid-rich= intramuscular myxoma, MLS, MFS (pretreatment with hyaluronidase results in loss of positivity) Chondroitin sulfate-rich= ESMC & chordoma (hyaluronidase resistant positivity) Case 9: 30-year-old male telephone lineman with 2.5cm right palmar mass, first noticed after hitting his hand while roofing. Increasing in size over the last 10 months

51 Diagnosis? Myxoinflammatory fibroblastic sarcoma (MIFS) 51

52 MIFS: Clinical Distinct low-grade sarcoma of distal extremities characterized by a mixture of myxoid, inflammatory & hyalinized zones Acral sites; 2/3 upper extremity, 1/3 lower extremity, rarely proximal trunk Potential for destructive local recurrence; rare lymph node & lung metastases Middle-aged adults; no sex predilection Slow-growing, occasionally painful mass Frequent local recurrence, occasionally necessitating amputation; adjuvant radiotherapy for selected cases MIFS: Pathologic Features Hyalinized, inflammatory & myxoid zones Bizarre tumor cells with giant macronucleoli (virocyte- & Reed- Sternberg-like) Pseudolipoblasts in myxoid areas Mixed acute and chronic inflammation Low mitotic rate Infrequent necrosis CD %, occasional focal CK & SMA 18% TGFBR3 &/or MGEA5 rearrangements* Hemosiderotic fibrolipomatous tumor Pleomorphic hyalinizing angiectatic tumor *Boland & Folpe. Hemosiderotic fibrolipomatous tumor, pleomorphic angiectatic tumor and myxoinflammtory fibroblastic sarcoma: Related or not? Adv Anat Pathol 2017 Apr 3 (Epub ahead of print) MIFS MIFS MIFS 52

53 MIFS: Differential M. Cheloniae Infection/inflammatory process Special stains and cultures+ Myxofibrosarcoma Distinct vessels, more atypia, less inflammation Giant cell tumor of tendon sheath Rarely myxoid and admixed with areas of typical GCTT, osteoclast type giant cells and secondary elements often present Hodgkin lymphoma Hematolymphoid markers positive, not as myxoid Inflammatory myofibroblastic tumor Marks with smooth muscle markers and ALK in a subset, no virocyte- or ganglion-like atypical cells typically present, more spindled, less myxoid M. Cheloniae GCTTS 53

54 GCTTS GCTTS Hodgkin lymphoma Hodgkin lymphoma CD30 CD15 MFS- Myxoid MFH MFS- Myxoid MFH 54

55 IMT IMT Take home messages myxoid pattern Certain features are more important to assess for this pattern Clinical Younger patients (MLS), older patients (MFS) Growth pattern Mutinodular (ESMC, MFS, MIFS), diffuse (fasciitis), infiltrative (aggressive angiomyxoma) Presence or absence of vasculature Little to none (myxoma), plexiform (MLS), curvilinear (MFS), arcuate (LGFMS) Cellularity Low (myxoma), high (MFS) Cells touching (ESMC), little cell-to-cell interaction (MLS) Inflammation MIFS (chronic inflammation), Intramuscular myxoma (absent) Acknowledgements Thank you to my colleagues Steve Billings and Patrick Shenjere for sharing PPT slides used in this talk. 328 Congrats soldier you have graduated from boot camp! 55