Malignant Sertoli cell tumor in the retained abdominal testis of a unilaterally cryptorchid horse.

This research paper documents the case of a 13-year-old Morgan horse that seemingly developed a rare form of cancer called malignant Sertoli cell tumor in a concealed testis within its abdomen, which resulted in metastases in the liver, spleen, lungs, and sublumbar lymph nodes.

Background

• The study focuses on a Morgan gelding, a horse breed typically used for riding, which was assumed to be a gelding (castrated horse) as per its appearance.
• A concealed testis was found in the right retroperitoneal space of the horse’s abdomen during necropsy, which contradicted the gelding classification.

Detection and Diagnosis

• The presence of neoplastic cells, which typically constitute developing tumors, was noted in the hidden testis of the horse.
• During immunohistochemical examination (a technique which identifies the presence and distribution of specific cellular components), the unidentified mass within the abdomen was confirmed to be a malignant Sertoli cell tumor, named after the specific cells it originates from in the testis.

Additional Findings and Context

• The concealed testicular cancer had already spread to other vital organs by the time of detection, with metastases found in the liver, spleen, lungs, and sublumbar lymph nodes.
• Testicular tumors are generally rare in stallions, more so the Sertoli cell tumors. Seminomas, another type of testicular tumor, are relatively more common in occurrence.
• Due to the rarity and limited reporting of Sertoli cell tumors in horses, there is little known about its typical biological behavior.
• Prior to this study, only two other known reports of Sertoli cell tumors in horses existed, both in descended testes (not concealed/retained within the abdomen), with only one of them being malignant in nature.