RESUMO
Malignant melanoma with infiltration into the bone marrow is seldom reported in the literature, for they are exceedingly rare. The primary site is not always apparent and a sizeable number of cases have been attributed to an occult primary. Metastasis to bone marrow is a terminal event usually occurring in stage IV of the disease and can be a focus of residual tumor cells which can cause a relapse.The current documentation is of a case of melanoma occurring as a rectal primary with anemia, thrombocytopenia, and leukoerythroblastic reaction. The marrow aspirates and trephine biopsy showed round to spindle-shaped malignant cells with intracytoplasmic brown-black coarse pigment, suggestive of melanin. The patient was diagnosed with stage IV melanoma but was lost for follow-up. The recognition of such an entity is important for both pathologists and clinicians alike. This case is being reported for the novelty of such an occurrence.