altrenogest and Ovarian-Neoplasms

An aggressive mare, presented for prebreeding examination, was found to have a significantly enlarged ovary (soccer ball size). A granulosa thecal cell tumor was initially suspected. Following laboratory and repeated clinical examination, the mare was diagnosed with an ovarian hematoma, which regressed with treatment.

Topics: Animals; Behavior, Animal; Diagnosis, Differential; Estrus; Female; Granulosa Cell Tumor; Hematoma; Horse Diseases; Horses; Ovarian Diseases; Ovarian Neoplasms; Thecoma; Treatment Outcome; Trenbolone Acetate

A 9-year-old Arabian mare was admitted for evaluation of multiple subcutaneous nodules and infertility. Fine-needle aspiration of one of the subcutaneous nodules resulted in a cytologic diagnosis of histiolymphocytic lymphoma. Palpation per rectum and transrectal ultrasonography revealed a mass associated with the left ovary. Excision of the ovarian tumor was performed, and a histopathologic diagnosis of granulosa-theca cell tumor was made. After removal of the granulosa-theca cell tumor, subcutaneous nodules regressed. The referring veterinarian reported that the nodules had also disappeared and then recurred after administration of a synthetic progestin. To further characterize the lymphoma and investigate this possible hormonal relationship, immunophenotyping and estrogen and progesterone receptor assays were performed. The subcutaneous lymphoma was classified as a T-cell rich B-cell lymphoma, results of estrogen receptor assays were negative, and results of progesterone receptor assays were positive. Clinical observations of subcutaneous lymphoma in horses indicate that the waxing and waning nature of these tumors may be associated with the estrous cycle, pregnancy, foaling, and lactation. Clinical observations and identification of progesterone receptors suggest that a relationship between serum steroid hormone concentrations, such as estrogen and progesterone, and subcutaneous lymphoma may exists.

Topics: Animals; Biopsy, Needle; Female; Granulosa Cell Tumor; Horse Diseases; Horses; Lymphoma, Non-Hodgkin; Neoplasm Recurrence, Local; Neoplasm Regression, Spontaneous; Neoplasms, Multiple Primary; Ovarian Neoplasms; Periodicity; Progesterone Congeners; Receptors, Progesterone; Thecoma; Trenbolone Acetate