Malignant ovarian tumors in two heifers.

Abstract

Granulosa cell tumors (GCTS) are the most common ovarian tumor of cattle. Although there is some disagreement on the clinical behavior of these neoplasms, they are typically composed of well-differentiated cells, and malignancy in unselected bovine populations is uncommon. This report describes poorly differentiated, malignant ovarian tumors with extensive peritoneal spread in 2 heifers. Two heifers from different farms were presented with marked abdominal distention. Heifer 1 was a weak, recumbent, emaciated, 180-kg, 9-month-old Holstein with poor growth and body condition. Heifer 2 was a lethargic, 454kg, 2-year-old Charolais heifer in fair condition. Clinical examination of both animals revealed a large abdominal mass, suspected to be an abscess, palpable per rectum. No abnormalities in sexual behavior had been noted. A poor prognosis was given, and the heifers were euthanized and necropsied. In both animals, 1 ovary was replaced by a large, dark red, solid to multiloculated cystic mass containing serosanguineous fluid and red-black, coagulated necrotic material. In heifer 1, a 30-cm-diameter mass was present at the tip of the right uterine horn (Fig. 1). The contralateral ovary was small (3.0 x 1.0 x 0.5 cm) and inactive. In heifer 2, a 26 x 12 x 12-cm mass was present at the tip of the left horn. Her right ovary contained a corpus luteum, and the right uterine horn contained a 15-cm fetus. Multiple (20 to 30) similar but smaller coalescing masses (5-15-cm diameter) were attached to the mesentery and abdominal serosa of both animals. One bronchial lymph node of heifer 2 was approximately 20 times normal size and contained a cystic mass similar to the abdominal masses. No other lesions were noted in either heifer. Selected tissues were fixed in 10% buffered formalin and prepared routinely for histology. The avidin-biotin complex immunoperoxidase method was used to stain deparaffinized tumor sections from heifers 1 and 2 with antibodies to cytokeratin (dilution 1:250) and vimentin (dilution 1:160) following standard techniques and appropriate controls, using an automated immunostainer. Additional tumor sections from heifer 2 were stained with antibodies from a routine diagnostic panel including ovarian carcinoma-associated antigen (CA 125, dilution 1:10), leukocyte common antigen (LCA, dilution 1:200), -smooth muscle actin (1A4, dilution 1:320), desmin (dilution 1:300), HMB45 (melanoma, dilution, 1:400), and S-100 (dilution 1:7,200). Positive controls were employed as follows: colonic adenocarcinoma for