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Case Reports

Abstract

Melanocytic neoplasms with fusion genes involving protein kinase C (PKC) homologs have been reported as blue nevus or pigmented epithelioid melanocytoma. However, a recent study by de la Fouchardière et al. revealed that melanocytic tumors with PKC fusion genes demonstrated characteristic histopathological features that were more similar to blue nevus than pigmented epithelioid melanocytoma. Herein, we report a case of melanocytic neoplasm associated with the PRKCB fusion gene. A woman in her 50s presented to a dermatology clinic with the chief complaint of a small nodule on her nose that had been present for 2 years. Physical examination revealed a 3-mm blackish nodule on her nasal dorsum. Blue nevus was clinically suspected, and an excisional biopsy was performed. Histopathological examination revealed a well-demarcated hyperpigmented nodule in the superficial to mid dermis that formed a dome shape. The cells forming the nodule exhibited biphasic morphology, comprising epithelioid cells at the core and spindle-shaped cells at the periphery. Both cell types contained significant amounts of melanin in the cytoplasm and did not demonstrate obvious nuclear atypia. Some tumor cells had small nucleoli. No junctional components consisted of melanocytes arranged in lentiginous or nested patterns. PRKCB break-apart fluorescence in situ hybridization revealed frequent split signals in tumor cells. Our case is suspected to be combined blue nevus histologically similar to pigmented epithelioid melanocytoma, considering previous studies, including those by de la Fouchardière et al.