Case of canine uterine adenocarcinoma with negative estrogen and progesterone receptor expression

A 12-year-old female mixed breed dog receiving a progesterone drug was referred for evaluation of an abdominal mass. Abdominal radiography and ultrasonography revealed a swollen uterus and an associated mass. Serum chemistry revealed hyperglobulinemia consistent with acute inflammation based on the results of serum protein electrophoresis. Fine needle aspiration of the mass guided by ultrasonography was performed for cytological evaluation. The cytological impression was consistent with adenocarcinoma. Exploratory laparotomy identified a uterine body mass, which was surgically removed for histopathology. Histology of the mass identified a uterine adenocarcinoma. Immunochemistry using anti-estrogen and progesterone receptor antibodies was performed and neoplastic cells were negative to both antibodies while some normal elements were reactive to both of them. Computer tomography demonstrated evidence of metastatic disease in the lung one week after the surgery and the dog died about 40 days after surgery.