Epithelioid blue nevus of the oral mucosa: a rare histologic variant

Abstract

An unusual variant of blue nevus known as the epithelioid blue nevus (EBN) was initially identified in patients with Carney’s complex—an autosomal-dominant disorder characterized by spotty skin pigmentations, cardiac myxomas, schwannomas, and endocrine overactivity. However, recent reports have identified sporadic cases of EBN in patients without any evidence of Carney’s complex. Typically, EBN clinically presents as a solitary, asymptomatic, small, darkly pigmented, dome-shaped cutaneous nodule. Unlike other more frequent variants of blue nevus primarily composed of spindled, pigmented melanocytes, EBN is characterized by a poorly circumscribed, dermal mass of large, well-defined, heavily pigmented, polygonal and epithelioid-shaped melanocytes intermixed with less densely pigmented epithelioid melanocytes and poorly defined, fusiform-shaped melanocytes. In contrast to other benign melanocytic proliferations, lesional cells in EBN exhibit little or no increased maturation correlated with deeper position in the underlying tissues. A recent report detailed 4 cases of EBN of the genital mucosa, with all other documented cases of EBN identified on the skin. Only 5 examples of EBN, including 1 sporadic EBN, have been identified in the head and neck. Blue nevi are the second most common form of nevus occurring in the oral cavity, but, to our knowledge, the epithelioid variant has not been recognized in the oral cavity. We now describe the first documented case of EBN involving the oral mucosa. The current report is that of a male patient who presented with EBN of the buccal mucosa. A brief review of the clinical and histopathologic features of previously reported cutaneous cases of EBN is presented.