Dermatopathology

Melanoma in Situ with Ulcer

The findings are those of a non-nevic pattern of de novo intraepidermal epithelioid melanocytic dysplasia. There is sufficient cytomorphologic and architectural atypia to warrant categorization as a melanoma in-situ of superficial spreading type.

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Slide 1: 65 year old man with an upper arm crusted papule. <br><br>The excision specimen shows a central zone of trauma with traumatic induced ulceration and background solar elastosis.

Slide 2: Higher magnification of the ulcerated area.

Slide 3: Closer inspection reveals an atypical melanocytic lesion characterized by dysplastic epithelioid melanocytes exhibiting a single cell and abortive dyshesive nested growth pattern along the dermal-epidermal junction.

Slide 4: The proliferation is not immediately apparent on H&E.

Slide 5: The extent of the proliferation is better highlighted by the double Ki-67/Melan-A stain which reveals extensive involvement of the entire excision specimen adjacent to the area of ulceration.

Slide 6: The proliferation is of high density with areas of pagetosis of abnormal melanocytes within the epidermis. There are a number of cells that do show double staining for Ki-67 (brown-nuclear) and Melan-A (red-cytoplasmic).

Slide 7: There is also extensive staining for HMB45.

Slide 8: The R21 preparation demonstrates the abnormal nature of this melanocytic proliferation by virtue of the extent of pan nuclear staining of lesional melanocytes for R21.