Diffuse melanosis secondary to metastatic malignant melanoma. Light and electron microscopic findings.

Tumor-free hyperpigmented skin from a patient with diffuse melanosis secondary to metastatic melanoma was examined by light and electron microscopy. Our findings indicate that the pathogenesis of this diffuse slate blue color is primarily to pigment deposition within perivascular dermal macrophages. We did not find intact melanosomes or individual tumor cell metastases in clinically normal skin, as has been previously reported.