Melanocytic Slide Club Case 202 Dr Richard A. Carr

M73. Pigmented lesion L cheek ?melanoma. Nov 2009

Results (N=28) BENIGN0 MALIGNANT28 –LMM19 –SSMM1 –Nodular1 –Min. Dev.1 –Spitzoid1 –Unclass.2

Results (N=28) Clark –I0 –II3 –III10 –IV5 –V1 Breslow –Median (range): 0.8 (0.3 to 1.7) Growth Phase: R = 1; V = 21 Regression: Y = 0; N = 20 Mitoses: Absent = 8; Low = 11

“Difficult definite LMM, ?deep dermal component” “Melanoma arising in LM mitoses 2/mm² “Favour LMM over unclassifiable” “Pigment synthesising melanoma / animal type - cell type similar to that described in pigmented epithelioid melanocytoma.” “Atypical proliferation of epithelioid cells in the epidermis with similar cells in the dermis. “ Expert Comments

Other Section (not circulated)

At 2 months: Wider local excision. Sampled in 2 TS. No Tumour

At 6 Months: Revision of Scar (keloidal)

At 18 Months: Local Recurrences x 3

Dermal Pigmented Epithelioid Cell Component (Dermal Nodule) Ball and Gorlitz 1994 Jam Acad Dermatol: 73 cases Clinical: 6.2mm mean dia. with central 1-5mm dark brown or black macule or papule of recent onset Ordinary acquired or congenital naevus Central focus or foci of large epithelioid melanocytes in variably sized nodular aggregates Heavily pigmented Cytologically bland or atypical Occupying 5 to 80% of naevus Associated melanophages Often transition of surrounding naevus Differential Diagnosis: Melanoma, Combined naevus

Melanocytic naevus with phenotypic heterogeneity (Atypical Dermal Nodule) v’s Melanoma Symmetrical v’s asymmetrical Size: often 1cm Lateral borders: Sharply v’s poorly defined Focus: present well demarcated v’s variable Atypia: absent or mild v’s moderate to severe Mitoses: Absent or minimal v’s frequent Lymphcytic reaction: Uncommon v’s frequent

Learning Points Beware of the epithelioid / pigmented clone in sun-damaged skin of the elderly!! Not all malignant lesions have a prominent host inflammatory reaction Mitotic figures may be sparse!