Evening Specialty Conference Bone and Soft Tissue Pathology. Case 1 Elizabeth G Demicco, MD, PhD Mount Sinai Hospital, New York Disclosure of Relevant Financial Relationships USCAP requires that all planners (Education Committee) in a position to influence or control the content of CME disclose any relevant financial relationship WITH COMMERCIAL INTERESTS which they or their spouse/partner have, or have had, within the past 12 months, which relates to the content of this educational activity and creates a conflict of interest. Disclosure of Relevant Financial Relationships Clinical History A 51 year old man presented with a painless mass in the left calf, which he had had for about one year. I have no conflicts of interest to disclose. Imaging findings Clinical History, continued Sag T1 Axial T1 FS post Tumor was biopsied. Diagnosis of low grade spindle cell neoplasm was rendered on scant biopsy material. A 5.7 cm tumor was resected with negative margins. 1
Differential Diagnosis Solitary Fibrous Tumor Low Grade Fibromyxoid Sarcoma Soft Tissue Perineurioma DFSP* A B C Differential diagnoses Diagnosis Why does it matter? Solitary Fibrous Tumor Intermediate malignant potential Metastasize in 5-20% of cases Low Grade Fibromyxoid Sarcoma Low grade malignancy High rate of LR if not treated appropriately, infrequently metastasize. Soft Tissue Perineurioma Benign. Low risk of LR, do not metastasize DFSP Locally aggressive. High risk LR, only metastasize if fibrosarcomatous transformation. DDiagnostic pitfalls in bone and soft tissue Epathology F 2
Solitary Fibrous Tumor Can arise in any anatomic site Deep > superficial Any age, M=F May be present for long duration prior to presentation Different SFT STAT6 IHC: positive nuclear STAT6 (c-term), BCL2, CD34, CD99 Pitfalls: very rarely express EMA, keratin, actin Low Grade Fibromyxoid Sarcoma Proximal extremities and trunk Deep > superficial Mostly young adults but may arise at any age May be present for long duration prior to presentation 3
LGFMS MUC4 IHC: Positive for MUC4, +/- EMA, CD34 Dermatofibrosarcoma Protuberans Superficial trunk and proximal extremities Young to middle age patients Slight male predominance Nodular/multinodular cutaneous mass, slow growing DFSP CD34 Soft Tissue Perineurioma Most common in extremities and trunk Superficial > deep Slight female predominance Arise at any age, more common in adults. IHC: CD34 positive Pitfalls: CD34 not specific. Rarely reported to express EMA 4
Perineurioma Perineurioma GLUT-1 EMA Perineurioma Variants IHC: Positive for EMA, GLUT-1, claudin, +/- CD34 Pitfalls: expression may be focal, may have focal S100 Sclerosing (cutaneous) Reticular/microcystic Intraneural Pseuodolipoblastic Epithelioid perineurioma Hybrid nerve sheath tumors with perineural differentiation Etc. 5
Morphology Collagen Blood vessels Infiltration Cells SFT Often ropy, thick, glassy Thin, dilated, branching staghorn LGFMS Fine, Giant collagen rosettes May be more hyalinized (SEFlike areas) Curvilinear to branching Perineurioma Variable Usually not prominent DFSP inconspicuous Rich vascular network Usually encapsulated Usually encapsulated Usually encapsulated Highly infiltrative, poorly circumscribed Variable Very bland with scant cytoplasm, to epithelioid Long delicate bipolar processes at least focally Spindled, moderate cytoplasm Immunohistochemistry CD34 SMA EMA GLUT1 CLAUDIN 1 MUC4 STAT6 SFT + +/- rare - - - + LGFMS -/+ +/- -/+ - - + - Perineurioma +/- -/+ + + + - - DFSP + +/- rare - - - - Molecular Diagnostics Back to the Case! Tumor type Molecular alteration Gene fusion SFT 12q inversion NAB2-STAT6 LGFMS t(7;16)(q22;p11), t(11;16) FUS-CREB3L2, FUS-CREB3L1 Perineurioma 22q deletions, mutations in NF2 DFSP Ring chromosomes, t(7;22)(q21.3;q13.1) COL1A1-PDGFB Diagnosis: Soft Tissue Perineurioma GLUT-1 CD34 IHC Positive: GLUT-1, CD34, Claudin-1 IHC Negative: EMA, S100, STAT6 FISH: negative for FUS translocation 6
Follow-up Patient is without recurrence after 4 months follow-up. Perineurioma Perineurioma Perineurioma DFSP Diagnostic pitfalls in bone and soft tissue SFT pathology LGFMS 7