Disseminated Histiocytic Sarcoma in Two Free-Living Florida Manatees (Trichechus manatus latirostris).

During necropsy of two manatees, masses in multiple organs including liver and spleen were identified. They were composed of neoplastic round to spindle-shaped cells, positive for vimentin, Iba-1, lysozyme, and Mac387, consistent with histiocytic sarcoma. One manatee also had an undifferentiated sarcoma that may have arisen from the histiocytic sarcoma.