Teat sinus and duct adenomatous hyperplasia in dogs

Seventeen lesions diagnosed as teat sinus and duct adenomatous hyperplasia were identified in 10 dogs. All of the dogs were small breeds. Six were spayed female and 4 were male, 3 castrated and 1 intact. In 5 cases, the lesions involved multiple teats. They were pink to black, flattened to round, and sometimes crusted. Histologically, the lesions were usually pigmented (16/17), plaque-like to nodular masses composed of polygonal cells arranged in anastomosing trabeculae and bilayered ducts and/or cysts, with a fibrous to mucinous (Alcian blue-positive) stroma and squamous cysts (12/17). Scattered epithelial cells contained single, discrete, clear cytoplasmic vacuoles. Atypia was mild, and the mitotic count per 2.37 mm2 varied from 0 to 15 (average 2.7). Immunohistochemistry was performed on 14 of the lesions from 8 dogs. Epithelial cells were 100% panCK+ and included basally located CK14+/CK5_6+/p63+/calponin− cells and nonbasal CK19+/CK7+ cells. Cells manifesting squamous differentiation were usually panCK+/CK14+/CK5_6+/CK19−/CK7−/p63±/calponin−. In addition to fibroblasts, vimentin positivity was found in disseminated, round to stellate stromal and intraepithelial cells that often had black, granular, cytoplasmic pigment (consistent with dendritic/phagocytic cells and/or melanocytes). Of the 8 dogs for which clinical follow-up information was available, all were still alive and well, with no significant teat changes, development of mammary lesions or other masses 4 to 22 months (median 12.5) after biopsy. The histologic, immunohistochemical, and clinical findings were consistent with teat duct and sinus adenomatous hyperplasia. This is an uncommon, benign proliferative lesion that can involve multiple teats of female and male, small breed dogs.

Gut-associated Lymphoid Tissue in the Large Intestine of Calves. I. Distribution and Histology

Gut-associated lymphoid tissue (GALT) in the large intestine was characterized in 12 calves (10 to 84 days old) obtained at necropsy (7, group A) or healthy animals (5, group B). Patches of mucosal lymphoid follicles were in all calves at ileocecal entrances (ICE), 23–42 cm distal to the ICE in the proximal loop of the ascending colon (proximal colon [PC] patch), and in the terminal rectum. PC patches varied from 8 to 30 cm in length. Solitary lymphoid follicles were found in the cecum of three calves, between the ileocecal entrances and the PC patch in four calves, adjacent to the PC patch in all calves, and in the ampulla recti. GALT occupied 7.8% of the large intestinal wall in animals of group A: 0.6% at the ileocecal entrance, 4.8% in the proximal colon, and 2.4% in the rectum. There were two different types of mucosal lymphoid follicles in group B: propria nodules with lymphoid follicles predominantly in the lamina propria, and lymphoglandular complexes with lymphoid follicles in the submucosa. In three 3-, 6-, and 7-day-old, germfree calves, distinct follicle-associated epithelium covered propria nodules and covering folds in depths of the lymphoglandular complexes; it was characterized by numerous intraepithelial cells and lack of goblet cells.