Granulosa-theca cell tumor associated with an ovulation fossa and normal ovarian stroma in a mare.

The research article discusses a unique case of a mare diagnosed with a granulosa-theca cell tumor in an ovary that still contained an ovulation fossa and normal ovarian tissue, which is atypical as these tumors commonly result in a spherical ovary without normal tissue.

The Case

• A mare was observed with ovarian enlargement and behavioral changes, signs often associated with ovarian tumors.

Initial Diagnosis and Surgery

• Before surgical intervention, an ultrasonographic examination was employed to investigate the suspected anomaly. The ovary displayed a multicystic appearance with no palpable ovulation fossa present during a per rectum examination.
• Despite these initial observations, during surgery, the affected ovary was found to reside within normal size limits. However, it had an unexpected enlargement on one side and contained an ovulation fossa—a significant finding since granulosa-theca cell tumors usually obliterate the ovulation fossa.

Confirmation of Diagnosis and Treatment

• The diagnosis of a granulosa-theca cell tumor was substantiated by the atrophy (shrinkage or wastage) of the infundibulum (the funnel-shaped opening to the fallopian tube near the ovary) in the affected ovary. This abnormality led to its surgical removal as a form of treatment.
• Subsequent monitoring showed that the mare’s testosterone concentrations remained within normal limits.

Unusual Findings

• Typically, granulosa-theca cell tumors are associated with a spherical ovary without an ovulation fossa or normal ovarian tissue. This is due to these growths’ propensity to ablate (remove or destroy) these features.
• However, this case presented a peculiar scenario where, despite the presence of the granulosa-theca cell tumor, the ovary continued to host an ovulation fossa and normal ovarian tissue, challenging the traditional understanding of this type of tumor.