RESUMO
A 5-year-old intact male German Shepherd dog was referred with a diagnosis of leishmaniasis. Several testicular masses were palpated during the physical examination, while the diagnostic screening yielded no remarkable findings. Fine needle aspiration cytology of the masses revealed the presence of intermediately differentiated mast cell tumours. Scrotal ablation and orchiectomy were performed as a definitive treatment option. The pathological examination of the surgical specimens confirmed the diagnosis of grade II mast cell tumours and showed that they were all confined to the testicular capsule. At 7 months post-admission, the dog exhibited neither postsurgical complications nor metastatic foci and was, therefore, given a favourable prognosis. Despite their exceptionally rare occurrence, mast cell tumours should be considered for the differential diagnosis of testicular tumours.