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Case Study
Aberrant PRAME expression in acral nevus
A 70-year-old male presented with a atypical melanocytic proliferation on his right instep. He had no personal or family history of melanoma. The clinical diagnosis was acral nevus - rule out atypia.
Case details
A 70-year-old male presented with a atypical melanocytic proliferation on his right instep. He had no personal or family history of melanoma. The clinical diagnosis was acral nevus - r/o atypia.
In volar skin, there are a few banal nevus cells in the upper dermis and a broader lentiginous proliferation of melanocytes along the dermoepidermal junction accompanied by hyperpigmentation of the basal epidermis. The junctional melanocytes have dendritic features and slightly irregular contours, and there is slight upward scatter of solitary melanocytes in the epidermis, compatible with site-related features on acral skin. Regular columns of pigmented pseudoparakeratosis are present overlying the bases of cristae profundae limitantes.
Mart-1 fails to reveal signification junctional melanocytic confluence or more extensive pagetoid spread. PRAME demonstrates nuclear expression within the junctional melanocytes, whereas the dermal melanocytes are PRAME-negative. The lesion extends to the peripheral margins.
Preliminary diagnosis:
Acral compound nevus with mild atypia and aberrant PRAME expression
MyPath Melanoma gene expression profile resulted in a score of -3.1 which is suggestive of a benign neoplasm.
Unexpected expression of PRAME led to an uncertain malignant potential in a suspected nevus. With benign MyPath Melanoma test results, the dermatopathologist was able to confirm a diagnosis of a benign acral lesion. While close monitoring or complete removal was recommended due to the positive margins, the patient avoided a wide local re-excision in a sensitive and surgically challenging area.
