Hemangiomas and hemangiosarcomas in inbred laboratory mice

Hemangiomas and hemangiosarcomas are rare, naturally developing tumors of blood vessels. In a retrospective study covering a period of 57 contiguous months between 1986 and 1991, four cavernous hemangiomas, eight capillary hemangiomas, and three hemangiosarcomas developed spontaneously in A/J, BALB/cJ, BALB/cByJ, C57BL/6J, NU/J, and 129/SvJ inbred mouse strains. When data were correlated to actual numbers of each sex in the colony, no sexual dimorphism was determined. At the time of submission, mice ranged in age from 100 to 434 days, with a mean of 217 days. Tumors principally affected the skin but were also diagnosed in the seminal vesicles, liver, muscle tissue, and cerebellum. Immunohistochemistry, with antisera directed against human von Willebrand factor (factor VIII-related antigen) as an endothelial cell marker, labeled mouse endothelial cells inconsistently. A monoclonal antibody directed against the smooth muscle actin isoform, but not the sarcomeric muscle actin isoform, outlined vascular structures in tumors and normal vascular smooth muscle in adjacent normal tissues.