Uterine Polyp in a Rat
History: A two year old black and white female intact rat with chronic non-responsive skin lesions.
In this case there was multifocal ulcerative dermatitis (not shown)
Uterus: Filling the uterus is a pedunculated mass of mature collagenous connective tissue with sparse number of fibroblasts covered by endometrial epithelium.
This is a fairly common lesion in aging rats. Polyps can be adenomatous or primarily stromal like in this case. There are usually small to moderate numbers of neutrophils, lymphocytes and plasma cells infiltrating the polyp.
Ulcerative dermatitis is commonly caused by Staphylococcus aureus in rats.
Mor, N and Lutsky, I. Spontaneous endometrial tumours of ‘Sabra’ rats. Laboratory Animals (1986) 20, 316-320.
Percy, DH and Barthold, SW. Pathology of Laboratory Rodents and Rabbits, 3rd edition. Blackwell Publishing Professional , Iowa, 2007.