A 54-year-old man presented with painless right testicular swelling 3 weeks in duration and a remote history of epididymo-orchitis treated with antibiotics. He also reported mild nocturia and frequency. On physical examination the right testis was abnormally firm, nontender and slightly enlarged. Scrotal ultrasound revealed an enlarged (6.3 3.6 4.2 cm), heterogeneous and hypoechoic right testis with slightly increased flow on color Doppler imaging (figs. 1 and 2). No abnormality of the ipsilateral epididymis was present. Given the high suspicion of malignancy, radical orchiectomy was performed. Final pathological diagnosis was idiopathic granulomatous orchitis (IGO). IGO is a rare inflammatory condition of the testis. It was first described in 1926 by Grunberg, and is characterized by chronic inflammation with granulomas in the testicular interstitium or tubules with destruction of spermatogenic cells. Although granulomatous orchitis may result from a specific infectious etiology, including Mycobacterium tuberculosis, Mycobacterium avium, brucellosis and actinomycosis, the etiology of