Combined Chemotherapy and Radiotherapy in Juvenile Feline Mediastinal Lymphoma: Two Cases

Mediastinal lymphoma is a common malignant hematopoietic tumor in cats, associated with poor outcomes, particularly in young individuals.While chemotherapy is the standard treatment, radiotherapy is commonly used for localized lymphoma.This report describes two young cats, an 11-month-old spayed female Domestic Shorthair cat (Case 1) and a 3-month-old neutered male British Longhair cat (Case 2) presented with acute dyspnea, and were diagnosed with T-cell mediastinal lymphoma.Ultrasound-guided fine-needle aspiration (FNA) of the mediastinal mass revealed a predominance of lymphoblasts in both cases, raising strong suspicion for lymphoma.Diagnosis was confirmed by polymerase chain reaction for antigen receptor rearrangement (PARR) in Case 1 and immunohistochemistry (IHC) in Case 2. Both cats received cyclophosphamide, vincristine, and prednisolone chemotherapy, resulting in a partial response.Radiotherapy (4 Gy per fraction per day for 5 days) was administered one week after chemotherapy in Case 1 and one month later in Case 2. Complete responses were achieved at two weeks and four months post-radiotherapy in Cases 1 and 2, respectively.At the last follow-up, both cats remained in remission for 46 and 16 months.These findings suggest that combining radiotherapy with chemotherapy may serve as an alternative treatment option for feline mediastinal lymphoma and could be particularly beneficial in juvenile cases.