<div>Background: Mouse mammary tumor is a common neoplasm of the species. Mice is an established model for human breast cancer studies and in recent times for transgenic studies. Hemangiomas are tumors of blood vascular system. Hemangioma with breast cancer is reported in human beings. Presented study describes an unusual case of concurrent mouse mammary tumor and cavernous hemangioma from Mizoram, India. 
 
Methods: A mortality of 8 out of a colony of 25 female albino mice was observed due to mammary tumors. Dead mice were thoroughly necropsied and tissue samples were collected from different parts of each tumor mass and fixed in neutral buffered formalin. The fixed tissues were processed for hematoxylin and eosin staining by routine paraffin embedding, microtomy and staining protocol.&nbsp; 
 
Result: Gross examination revealed variable sized tumors on abdomen of affected mice. Histopathology revealed two different forms of mammary tumor viz, acinar and solid mammary carcinoma. Most peculiar finding was remarkable presence of large, endothelial lined cavernous spaces with presence of stagnant blood. These were diagnosed as cavernous hemangioma. Perusal of available literature did not reveal any report of cavernous hemangioma occurring with mouse mammary tumor, while it is found in other species including human beings.</div>

Spontaneous Mammary Tumor with Concurrent Cavernous Hemangioma in Albino Mice- A Rare Case Report from Mizoram, India