Etiology:  Adenocarcinomas arise from the glandular epithelium of the mammary tissue.

Incidence:  The incidence of mammary adenocarcinoma is common.

Clinical Signs:  Mammary adenocarcinomas may be located nearly anywhere in the subcutaneous region due to the extensive distribution of mammary tissue in the mouse (A.).

Pathology:  Mammary tumors are usually large, soft, fleshy, well vascularized and may contain necrotic tissue and/or blood-filled cysts. Histologically, mammary adenocarcinomas are often highly pleomorphic with a loss of alveolar differentiation (B.).  They often contain variably sized cystic structures lined by pleomorphic to anaplastic acinar cuboidal epithelium (C.) and can be encapsulated or unencapsulated [1].

Diagnosis:  Diagnosis can be made upon necropsy and histopathologic examination of tissue.

1.            Pathology Of The Mouse. 1 ed1999, 2850 Oak Grove Road, Vienna, IL, 62995: Cache River Press