Hemangiomas and hemangiosarcomas are rare, naturally developing tumors
of blood vessels. Ln a retrospective study covering a period of 57 co
ntiguous months between 1986 and 1991, four cavernous hemangiomas, eig
ht capillary hemangiomas, and three hemangiosarcomas developed spontan
eously 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 su
bmission, 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, Immunohist
ochemistry, 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 muscl
e actin isoform, outlined vascular structures in tumors and normal vas
cular smooth muscle in adjacent normal tissues,