Syphilis always begins as orchitis with secondary involvement of the epididymis.
It may present as isolated orchitis without involvement of adnexal structures.
Orchitis may occur in both congenital and acquired syphilis.
Microscopically, syphilis may produce nodular gummas ( Syphilitic Gumma ) or diffuse interstitial inflammation. Interstitial changes include edema, lymphocytic and plasma cell infiltration and typical obliterative endarteritis with perivascular cuffing of lymphocytes and plasma cells. Gradually, there is complete loss of seminiferous tubules and interstitial cells.