The epithelioid blue nevus. A multicentric familial tumor with important associations, including cardiac myxoma and psammomatous melanotic schwannoma.

We report on 21 pigmented nevi that occurred in 11 patients (6 male and 5 female patients) age 3 to 39 years. All patients had the Carney complex (myxomas, spotty skin pigmentation, endocrine overactivity, and schwannomas); six patients were members of three families. The nevi occurred on the extremities and trunk, less frequently on the head and neck, and were multiple in five patients. Clinically, they were darkly pigmented, domed, and small (less than 1 cm) and commonly interpreted as "blue nevi." Microscopically, they featured heavily pigmented, poorly circumscribed, dermal lesions that displayed two types of melanocytes: one intensely pigmented, globular, and fusiform; the other lightly pigmented, polygonal, and spindle. The melanocytes were situated among the dermal collagen bundles singly, in short rows and small groups, and occasionally in fascicles. Nuclei of the lightly pigmented, polygonal and spindle cells were vesicular with very pale chromatin and a single prominent nucleolus. Seven tumors were each part of a combined nevus. After excision, none of the tumors recurred or metastasized. The epithelioid blue nevus is important because of its strong association with the Carney complex. Therefore, affected patients (and their relatives) should be considered at risk for other elements of the syndrome, especially cardiac myxoma.