Background: T-cell lymphomas involve the testis infrequently, which deserve special attention because of the poor prognosis and the need to make an appropriate diagnosis, which could lead to a better therapeutic strategy.
Case presentation: A 40-year-old man presented with right testicular swelling for past three months. The swelling was painless, hard and rubbery. Testicular ultrasound showed diffuse increase in size of the testicle, with alteration in its echogenicity. The patient underwent orchidectomy, and based on histopathological and immunohistochemical tests, a peripheral T-cell lymphoma, not otherwise specified was diagnosed.
Conclusion: Testicular peripheral T-cell lymphomas are rare and aggressive cancers, with clinical differentials of seminoma and non-neoplastic conditions.