Melanocytic Tumours. Molecular Biology 02/06/2015. Cutaneous Melanocytic Tumours Introduction. Thomas Brenn. Intermediate Malignancy

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1 Cutaneous Melanocytic Tumours Introduction Melanocytic Tumours: Update on Epidemiology and Molecular Biology Thomas Brenn Wide clinical and morphological spectrum Ranging from benign naevi to melanoma Majority benign Separating benign from malignant poses significant clinical and histological challenge Most important: identification of predictors of outcome Melanocytic Tumours Naevi Melanoma Common acquired naevi SSM Congenital naevi Nodular M Special site naevi Acral lentiginous M Dysplastic naevi Lentigo maligna M Sclerosing naevi Desmoplastic M Blue Naevi Mucosal M DPN Lentiginous M Blue naevus like M Uveal M Cutaneous Melanocytic Tumours Intermediate Malignancy Spitzoid melanoctic tumours Pigmented epithelioid melanocytoma (Pigment synthesising melanoma) 1

2 Melanoma Epidemiology The 20 Most Common Cancers in 2011 Number of New Cases, UK The 10 Most Commonly Diagnosed Cancers: 2012 Estimates Total Number and Percentage of New Cases Diagnosed per Year, Worldwide Malignant Melanoma (C43): Anatomical Distribution Average Number of New Cases Per Year and Age-Specific Incidence Rates per 100,000 Population, UK Malignant Melanoma (C43) Percentage Distribution of Cases Diagnosed on Parts of the Body, by Sex, UK,

3 Risk Factors Fair skin Sun exposure chronic sun exposure intermittent sun exposure, repeated burns Increasing age Large number of atypical naevi Giant congenital naevi Family and personal history of melnanoma Deficient immune system Xeroderma pigmentosun Malignant Melanoma (C43): Melanoma Incidence European Age-Standardised Incidence Rates per 100,000 Population, by Sex, Great Britain Melanoma Mortality Melanoma Survival Malignant Melanoma (C43): European Age-Standardised Mortality Rates per 100,000 Population, UK Malignant Melanoma (C43): Net Survival up to Ten Years after Diagnosis, Adults (Aged 15-99), England and Wales 3

4 Melanoma Survival Malignant Melanoma (C43): Age-Standardised Five-Year Net Survival, England and Wales Malignant Melanoma (C43): Melanoma Survival Five-Year Relative Survival (%) by Stage, Adults Aged 15-99, Former Anglia Cancer Network Malignant Melanoma (C43): Proportion of Cases Diagnosed at Each Stage, Adults 15-99, Former Anglia Cancer Network Stage Men Women Adults Stage I 61.4% 71.3% 66.4% Stage II 21.0% 17.1% 19.1% Stage III 13.7% 8.5% 11.1% Stage IV 2.0% 0.7% 1.3% Stage not known 1.9% 2.4% 2.1% All stages 100.0% 100.0% 100.0% 4

5 Tumour thickness Anatomic level Mitotic activity Ulceration LN Metastasis Distant Metastasis Prognostic Factors Melanoma Diagnosis Clinical presentation Histological features Immunohistochemistry Molecular Biology Melanoma Clinical Worrying clinical features: Asymmetry Irregular Borders Colour variation Diamter >5mm Evolution (any change in appearance, including ulceration and bleeding) Superficial Spreading Melanoma Most frequent subtype of melanoma Prognostic information on melanoma is based on SSM Caucasians Adulthood, increasing incidence with advanced age Sites of intermittent sun exposure Extremities and trunk Enlarging and changing pigmented lesion 5

6 Melanoma Morphological Spectrum Superficial Spreading Melanoma Nodular Melanoma Lentigo Maligna Melanoma Acral Lentiginous Melanoma Lentiginous Mucosal Melanoma Desmoplastic Melanoma Naevoid Melanoma Spitzoid Melanoma Pigment Synthesizing Melanoma Malignant Blue Naevus Balloon Cell Melanoma Metaplastic Melanoma Myxoid Melanoma Signet Ring Cell Melanoma Small Cell Melanoma Melanoma Variants Clinical setting Histological features Diagnostic criteria Specific differential diagnosis Immunohistochemical phenotype Genetic profile Prognosis and behaviour 6

7 Melanoma Immunohistochemistry S100 Sox10 Melan A/Mart 1 HMB45 MITF MIB1 cyclin D1 p53 bcl2 p16 p21 BRAF, NRAS, CKIT, ALK, ROS, BAP1 S100 S100/SOX10 Melan A First line melanocytic marker: High Sensitivity for melanocytic tumours Expressed in Naevi and Melanoma Low specificity, also seen in neural and myoepithelial neoplasms Best marker in desmoplastic melanoma May be weak and focal in benign and malignant blue naevi S100 Second line melanocytic marker: Good sensitivity for epithelioid melanocytic tumours But often lost in spindle cell melanoctic neoplasms Expressed in Naevi and Melanoma Relatively high specificity, but also seen in PECOMA Useful for evaluation of junctional component Often strong and diffuse in benign and malignant blue naevi Melan A 7

8 HMB 45 Second line melanocytic marker: Low sensitivity but high specificity Highlights maturation with dpeth in naevi Expression in deep component seen in DPN/blue naevi, melanoma and metastasis Useful for evaluation of junctional component HMB45 HMB45 Micropthalmia Transcription Factor Third line melanocytic marker: High sensitivity but low specificity MITF MIB1/Ki67 Proliferation marker: Low expression in naevi High expression in deeply invasive and metastatic melanoma Many pitfalls: Interpretation in thin melanoma and intermediate thickness tumours difficult Low proliferation index in desmoplastic melanoma MIB1 8

9 Cyclin D1 Little diagnositc/prognostic value Highlights maturation in naevi Diffuse expression: concerning for melanoma but rare phenomenon limited to deeply invasive tumours also seen in Spitzoid neoplasms MIB1 CyclinD1 P16 Melanoma Genetics Diffuse expression in naevi, including Spitzoid tumours Loss of expression: in subset of melanoma in Spitzoid tumours concerning for more aggressive behaviour Rapid progress over past 15 years: genomic instability of melanoma development of diagnostic FISH assay p g y mutational analysis and targeted therapy P16 Garrido Ruiz MC, et al. Mod Pathol. 2010;23(9): Kapur P, et al. ModPathol. 2005;18(2):

10 Melanoma Genetics Comparative Genomic Hybridisation Frequent chromosomal aberrations in melanoma (>95%) in contrast to benign naevi 13 regions on 8 chromosomes Bastian BC, et al. Am J Pathol 2003;163(5): Melanoma Genetics Melanoma FISH Using CGH data a panel of 4 probes was found most informative: Centromere chromosome 6 Gain of CCND1 (11q13) Gain of RREB1 (6p25) Loss of MYB (6q23) Sensitivity of 87% and specificity of 96% Recent inclusion of probe for 9p21 as marker of prognosis Technically demanding and expensive Fluorescence In Situ Hybridization as an Ancillary Tool in the Diagnosis of Ambiguous Melanocytic Neoplasms: A Review of 804 Cases. North, Jeffrey; Garrido, Maria; Kolaitis, Nicholas; LeBoit, Philip; McCalmont, Timothy; Bastian, Boris American Journal of Surgical Pathology. 38(6): , June DOI: /PAS Mutational Spectrum in Melanoma Whole exome sequencing: numerous (>1,000) gene mutations Challenge: Driver vs bystander mutations Inactivating mutations in CDKN2a (40 80%) PTEN (30 70%) Promoter mutations in TERT gene FIGURE 9. Polyploidy in FISH. All 4 FISH probes showing >2 signals. Red 6p25, Green 11q13, Yellow 6q23, Aqua centr omere by Lippincott Williams & Wilkins. Published by Lippincott Williams & Wilkins, Inc. 2 High rate of mutations in BRAF in 50% (vemurafenib) NRAS in 20% (MEK inhibitor MEK162) CKIT in 10% (imatinib) GNAQ/GNA11 10

11 Uveal Melanoma Lentigo Maligna Vulval Melanoma Mutations in GNAQ and GNA11 gene mutations Additional BAP1 mutations may predict more aggressive behaviour GANQ and GNA11 gene mutations also observed in blue naevi and blue naevuslike melanoma ( malignant blue naevus ) Acral Melanoma Van Raamsdonk CD, et al. Nature. 2009;457(7229): Van Raamsdonk CD, et al. N Engl J Med. 2010;363(23): Familial Melanoma Familial Melanoma CDKN2a Familial atypical multiple mole melanoma (FAMM)/Dysplastic nevus syndrome 40% of familial melanoma Autosomal dominant Multiple atypical naevi and melanoma Superficial spreading and nodular melanoma POT 1 Recently described Loss of function mutations in the Protection of telomers 1 (POT 1) gene on chromosome 7q31 4% of familial melanoma Also linked to chronic lymphocytic leukemia (CLL) Robles Espinoza CD, et al. Nat Genet. 2014;46(5): Shi J, et al. Nat Genet. 2014;46(5):

12 BAP1 Familial Melanoma BAPoma Tumour suppressor gene mutations in BRCA1 associated protein 1 (BAP1)on chromosome 3q21 Autosomal dominant t Multiple melanocytic tumours with epithelioid cell change Uveal and cutaneous melanoma Mesothelioma Renal cell carcinoma Wiesner T, et al. Nat Genet. 2011;43(10): Wiesner T, et al. Am J Surg Pathol 2012;36(6): courtesy Dr Zlatko Marusic, Zagreb, Croatia BAP1 BRAF Pigment Synthesising Melanoma Pigment Synthesizing Melanoma Pigmented Epithelioid Melanocytoma Animal/Equine type Melanoma Unusual distinctive melanocytic tumour Reminiscent of melanomas in grey horses Animal / Equine type Melanoma Significant morphological overlap with epithelioid blue naevus in Carney complex Pigmented Epithelioid Melanocytoma Loss of expression of Protein Kinase A Regulatory Subunit 1a (PRKAR1A) in sporadic PEM and EBN in patients with Carney complex {Zembowicz A et al Am J Surg Pathol 2007; 31: } 12

13 Pigment Synthesising Melanoma Clinical Presentation Deeply pigmented tumours Extremities, head & neck, trunk Mucosa, genital sites Young adults (20 30 yrs) Wide age range including congenital onset M=F 13

14 9 year old boy with a pigmented lesion on the left superior deltoid area 14

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16 Pigment Synthesising Melanoma Histological Features Deeply pigmented tumours Invasion of Level IV or V Tumour thickness: 2 3 mm (range: mm) Large ovoid to polygonal cells Heavily pigmented cytoplasm and vesicular nuclei with prominent nucleoli Low mitotic rate No or minimal junctional component Pigment Synthesising Melanoma Clinical Behaviour Overall favourable prognosis High rate of LN metastasis (30 50%) Rare distant metastasis to liver Rare documented mortality (limited follow up) {Antony FC Histopathology 2006;48: } {Zembowicz A et al Am J Surg Pathol 2004;28:31 40} {Mandal RV Am J Surg Pathol 2009;33: } Spitz Naevus Introduction One of the most challenging and controversial aspects of melanoctic tumour pathology to date Described by Sophie Spitz in 1948 as juvenile melanoma Favourable outcome despite worrying histological features Histological features poor predictor of outcome (disease associated mortality in 1/13 patients) Spitz Naevus Clinical Presentation Wide age spectrum but most common in childhood and adolescence Decreasing frequency with age Predilection for Caucasians Slight female predominance Wide anatomic distribution Face and ear in childhood Trunk and extremities in adulthood Non pigmented, red to skin coloured papule <1cm in diameter Calonje et al. McKee s Pathology of the Skin, 4 th ed. Elsevier

17 Spitz Naevus Problems 65 years after Sophie Spitz publication Poor insight into the biology of Spitz tumours Difficult to predict behaviour Classification into Spitz Naevus Atypical Spitz Tumour/Spitz Tumour of Uncertain Malignant Potential Spitzoid Melanoma Spitz Naevus Genetics Lack of mutation in NRAS, KIT, GNAQ, GNA11 HRAS mutations in ~10% (desmoplastic SN) Homozygous loss of BAP1 and BRAF mutation tti Kinase fusions involving ROS1, NTRK1, ALK, BRAF, RET in ~50% Spitz Tumours Busam KJ, et al. Clinical and pathologic findings of Spitz nevi and atypical Spitz tumors with ALK fusions. Am J Surg Pathol. 2014;38(7): Wiesner T, et al. Kinase fusions are frequent in Spitz tumours and spitzoid melanomas. Nat Commun. 2014;5:3116. Wiesner T, et al. A distinct subset of atypical Spitz tumors is characterized by BRAF mutation and loss of BAP1 expression. Am J Surg Pathol. 2012;36: Wiesner T, et al. Germline mutations in BAP1 predispose to melanocytic tumors. Nat Genet. 2011;43: Bastian BC, LeBoit PE, Pinkel D. Mutations and copy number increase of HRAS in Spitz nevi with distinctive histopathological features. Am J Pathol. 2000;157:

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20 S100 Melan a cyclin D1 MIB1 p16 p21 20

21 Morphological Spectrum of Spitz Naevi Pagetoid Spitz Acral Spitz Desmoplastic Spitz Pigmented Spitz and Spindle Cell Naevus (Reed) Deep Penetrating Naevus Atypical Spitz Naevus/Tumour/Stump Spitzoid Melanoma Desmoplastic Spitz Naevus Brown/erythemato us papules <1cm Adulthood F>M Extremities HRAS mutations 21

22 Kiuru M, Patel RM, Busam KJ. J Cutan Pathol. 2012;39(10):

23 Deep-pentrating naevus Wide age range; adolescence and early adulthood Face, neck, extremities Darkly pigmented to grayish symmetrical papule/nodule <1cm Closely related to Spitz Naevi Mutations in HRAS, but not GNAQ, GNA11 23

24 BAPoma Characteristic epithelioid melanocytic tumours with Spitzoid features Loss of BAP1 expression Additional BRAF mutation courtesy Dr Zlatko Marusic, Zagreb, Croatia Familial or sporadic Also seen in AST and cutaneous and uveal melanoma courtesy Dr Zlatko Marusic, Zagreb, Croatia Wiesner T, et al. Am J Surg Pathol. 2012; 36: Wiesner T, et al. Nat Genet ; 43: M, 28 Jahre, Gesicht BRAF BAP1 24

25 Spitz Naevus with Kinase Fusion Clinical, Histopathologic, and Genomic Features of Spitz Tumors With ALK Fusions. Yeh, Iwei; MD, PhD; de la Fouchardiere, Arnaud; MD, PhD; Pissaloux, Daniel; Mully, Thaddeus; Garrido, Maria; MD, PhD; Vemula, Swapna; Busam, Klaus; LeBoit, Philip; McCalmont, Timothy; Bastian, Boris; MD, PhD American Journal of Surgical Pathology. 39(5): , May DOI: /PAS ALK1 FIGURE 2. Disruption of ALK identified by FISH. A, Unbalanced rearrangement of the ALK gene, with preservation of the 3' signal (red) and the remaining intact ALK gene (1 juxtaposed green and orange signal). B, Balanced rearrangement of the ALK gene with separated orange and green signals compared with the remaining intact locus. C, Amplification of the 3' oncogenic signal (1 or 2 fusion signals + numerous clustered orange signals). Yeh I, et al. Am J Surg Pathol. 2015;39(5): Busam KJ, et al. Am J Surg Pathol. 2014;38(7): Copyright 2015 Wolters Kluwer Health, Inc. All rights reserved. Published by Lippincott Williams & Wilkins, Inc. 2 Atypical Spitz Tumour/ Spitzoid Melanoma Poorly defined criteria with poor interobserver agreement Constellation of features Atypical Spitz Tumour/Spitzoid Melanoma -Concerning Features- Architecture: Diameter in mm (>10 mm) Depth in mm (involvement of subcutaneous fat) Ulceration Poor circumscription Diffuse Pagetoid spread High cellular density Lack of zonation and maturation Asymmetry Few or no dull pink (Kamino) bodies Cytology: High nuclear to cytoplasmic ratios Loss of delicate or dispersed chromatin patterns Thickening of nuclear membranes Hyperchromatism Large nucleoli Proliferation: Significant mitotic rate Deep/marginal mitoses Increased mib-1 proliferation index Modified from: Barnhill RL. Modern Pathology. 2006; 19: S21-S33 25

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27 mib-1 27

28 mib-1 Melan a 2 year old girl; right ankle tumour 10 year old female with an enlarging lesion on the left calf present for 8 months 28

29 Melanoma in Children and Adolescents Nodular M Sp M PSM SSM Nevoid M n age (yrs) site H&N>E>T E>H&N>T H&N E>T E>T thick (mm) ulceration 50% 24% nil 0.8% nil necrosis 25% nil nil nil nil mitoses 6.5/mm 2 5/mm 2 1/mm 2 1/mm 2 2.5/mm 2 LN met 57% 24% 100% nil 30% Dist met 50% nil nil nil nil mortality 40% nil nil nil nil 29

30 AST/Spitzoid Melanoma -Prognose- In young children (<10 years): Favourable behaviour Risk for involvement of locoregional lymph nodes Rare disseminated disease and mortality Sentinel lymph node biopsy not helpful and should be avoided Spitzoid Melanoma No firm established diagnostic criteria Distinction from Atypical Spitz Tumour largely arbitrary Best avoided in young patients Lallas A, eta l. Lancet Oncol. 2014;15(4):e doi: /S (13) Duncan LM. Lancet Oncol. 2014;15(4): AST/Spitzoid Melanoma -Genetics- Homozygous but not heterozygous 9p21 deletion associated with more aggressive behaviour Yazdan P, et al. Comparative analysis of atypical spitz tumors with heterozygous versus homozygous 9p21 deletions for clinical outcomes, histomorphology, BRAF mutation, and p16 expression. Am J Surg Pathol May;38(5): Gerami P, Cooper C, Bajaj S, Wagner A, Fullen D, Busam K, Scolyer RA, Xu X, Elder DE, et al. Outcomes of atypical spitz tumors with chromosomal copy number aberrations and conventional melanomas in children. Am J Surg Pathol Sep;37(9): Gerami P, et al. Risk assessment for atypical spitzoid melanocytic neoplasms using FISH to identify chromosomal copy number aberrations. Am J Surg Pathol. 2013;37(5):