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  Diagnostic Quizzes
A solitary nodule of the right cheek

A 25-year-old man presented with a 1-year history of a small nodule on the right cheek. The nodule presented as an illdefined,
reddish lesion, with a diameter of 5 mm (Figure 1). The nodule was excised and subjected to pathological examination,
which revealed pleomorphic spindle and epithelioid cells infiltrating dermal collagen bundles. These cells showed
discernible downward maturation (Figure 2). Microscopic examination under a high-power field showed nuclear enlargement,
pleomorphism, and indistinct mitotic figures. Foci of Kamino bodies and scattered melanin deposition were detected
in the papillary dermis. Immunohistochemical analysis showed that the tumor cells had increased cytoplasmic expression
of anti-melan-A, HMB-45, and CD68, and that these cells were negative for the expression of CD34 and epithelial membrane
antigen (Figure 2). Immunoreactivity to Ki-67 antibody was scored as less than 2% positive cells. Total excision of the
lesion was then performed, and no recurrence was noted during follow-ups at our clinic approximately half a year later


fig 1
A dome-shaped reddish nodule


fig 2

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