Ovarian T-cell lymphoma in a dog with chronic protein-losing enteropathy.

[BACKGROUND] Lymphoma is one of the most common malignancies in dogs, but ovarian lymphoma is exceedingly rare, with only a few reported cases. Most canine lymphomas are of B-cell origin, whereas T-cell lymphomas are generally associated with a more aggressive clinical course. Protein-losing enteropathy (PLE) is a well-documented cause of hypoalbuminemia in dogs, often resulting from lymphangiectasia or chronic enteropathies. The potential relationship between chronic immune-mediated disease and the development of lymphoma remains unclear.

[CASE PRESENTATION] A 10-year-old intact female Miniature Poodle presented with chronic diarrhea, ascites and hypoalbuminemia. Abdominal ultrasound revealed severe intestinal mucosal striation, consistent with PLE, but no evidence of neoplasia. The dog was treated with methylprednisolone, chlorambucil, and cyclosporine, achieving long-term clinical stability. Fourteen months after initial presentation, the dog developed acute gastrointestinal signs, and ultrasound revealed an ovarian mass. Cytology, histopathology, and immunohistochemistry confirmed a diagnosis of ovarian T-cell lymphoma. No other neoplastic lesions were detected at that time raising the possibility of a primary ovarian origin, though widespread disease at necropsy suggests secondary involvement. The dog remained clinically stable for five months after lymphoma diagnosis but ultimately developed widespread disease, including hepatic, splenic, and adrenal involvement, leading to euthanasia. Necropsy confirmed multi-organ dissemination of the T-cell lymphoma, while histopathology of the intestines revealed signs of chronic lymphangiectasia but no definitive diagnosis of intestinal lymphoma.

[CONCLUSIONS] This case highlights the diagnostic challenges of extranodal lymphoma in dogs and the importance of considering neoplasia in cases of chronic protein-losing enteropathy. The potential role of chronic inflammation and long-term immunosuppressive therapy in lymphomagenesis remains unclear and warrants further study.