[Pigmented pheochromocytoma. Case report with immunohistochemical and electron microscopic characterization]

We present a case of pigmented adrenal paraganglioma in a 39-year-old female patient with associated neurofibromatosis type 1 (NF1). Histology showed features typical for phaeochromocytomas except for varying amounts of brown pigment within the cytoplasm of tumour cells, which proved to be melanin by histochemical and ultrastructural analysis. The occurrence of melanin is believed to reflect the origin of this neoplasm from multipotent cells of the neural crest. Pigmented phaeochromocytoma has to be taken in consideration in the differential diagnosis of pigmented neoplasms, especially in the adrenal gland, where it has to be discriminated from pigmented cortical adenoma (so-called black adenoma) and primary malignant melanoma.