Metastatic melanoma in the marrow: a black and white diagnosis

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A 62-year-old man presented with a 6-month history of progressive lethargy, generalized aches and pains, profuse sweats and weight loss. Prednisone, given for a presumed diagnosis of polymyalgia rheumatica, provided transient symptomatic relief. He had a past history of left ocular melanoma 16 years previously, treated with brachytherapy only, following which he suffered complete blindness in his left eye.

A blood count showed moderate anaemia and thrombocytopenia. The blood film was leucoerythroblastic. A bone marrow biopsy specimen was macroscopically strongly suggestive of metastatic melanoma (top). Trephine biopsy histology (bottom) showed extensive infiltration with melanoma cells, with melanotic and amelanotic areas. The melanotic areas corresponded to the black area macroscopically. A computed tomography scan showed multiple pulmonary, hepatic and peritoneal metastases. The patient is being treated palliatively.

Bone marrow metastasis is generally associated with a macroscopically pale trephine but the black appearance in this case led to the suspicion of melanoma metastasis.

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