Case 4

A 55-year-old man presented with a two-year history of a pigmented lesion of the left ear helix. Examination showed a 5.5-mm, symmetrical, dark brown, homogeneous macule with a smooth border (Figure 7).

Figure 7

A pigmented 6 mm papule is present on the left ear helix. The lesion is symmetrical, homogenous in color, and has a smooth border.

It was thought to be a seborrheic keratosis. One month later, the patient returned noting that the lesion had slowly grown; punch excision was performed. Histopathologic investigation showed a proliferation of melanocytes at the dermal-epidermal junction forming irregular nests. The melanocytes showed variation in nuclear shape, size, and chromatin pattern and were present at higher levels within the epidermis, and followed the dermal-epidermal junction into hair follicles (Figures 8a, 8b).

Figure 8a

A medium-power view showing in situ melanoma presenting as atypical lentiginous melanocytic hyperplasia.

Figure 8b

A medium-power view af another area showing pagetoid spread of atypical melanocytes.

No invasive growth was present. The diagnosis of malignant melanoma in situ was made.

© 1999 Dermatology Online Journal