Angiotropic metastatic malignant melanoma.

Three years after excision of a primary malignant melanoma from the lower back, a mass was noted in the right scapular region of a 51-year-old man. Histopathology revealed a malignant spindle-cell neoplasm invading the wall of a deep cutaneous blood vessel. Immunohistochemistry confirmed the diagnosis of angiotropic metastatic melanoma and ruled out primary leiomyosarcoma. Angiotropism is a rare pattern of metastasis of melanoma; the biochemical mechanisms that permit melanoma cells to undergo hematogenous dissemination, and the favorable milieu that the vascular wall offers for melanoma cells, may be responsible for this unusual growth pattern.