[Syphilitic orchitis: report of a case].

Syphilitic orchitis ir recently a rare disease in Japan. A 44-year-old man visited our hospital with the complaint of swelling of the right scrotum. He first noticed it about a half year ago, but the swelling mitigated without any therapy. The right testis was about the size of a hen's egg, elastic hard, and slightly rugged when he first visited our hospital. Treponema pallidum hemagglutination assay (TPHA) and rapid plasma reagin (RPR) were positive. We performed high orchiectomy because we could not deny the possibility of testicular tumor. Pathologically, granulomatous inflammation with lympho-plasmacytic infiltration and endoarteritis obliterans of the small arteries were seen in the specimen. It was diagnosed as granulomatous inflammation possibly caused by syphilitic orchitis. Syphilitic orchitis is usually quite difficult to distinguish from other types of granulomatous diseases of the testes, for example tuberculous orchitis. Various types of stains and careful examination of the specimen were thought to be necessary to distinguish these diseases.