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July 2010

Focally Pigmented Pink Plaque on the Back—Diagnosis

Author Affiliations


Arch Dermatol. 2010;146(7):789-794. doi:10.1001/archdermatol.2010.153-b

Histopathologic examination revealed an epidermis with focal lobules of basaloid cells with scant cytoplasm, hyperchromatic nuclei infiltrating into the superficial dermis with peripheral palisading, and focal stromal retraction with a lymphohistiocytic infiltrate. There is an interspersed melanocytic proliferation, consisting predominantly of atypical epithelioid-shaped single melanocytes and nests along the dermoepidermal junction with marked pagetoid changes (Figure 2). Furthermore, within the dermis, there are multiple dilated blood vessels with attenuated thin walls containing red blood cells (Figure 3). Immunohistochemical examination with Melan-A (Figure 4), HMB-45, and S-100 protein immunostains revealed atypical-appearing melanocytes and nests within the epidermal compartment.

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