Mumps is a systemic viral disease that most commonly affects school-aged children.
In adult males orchitis typically develops in about 1 week after onset of parotid inflammation, rarely, it may precede parotitis or occur in the absence of parotitis.
Orchitis occurs as a complication in 20 to 30% of cases of mumps and on 70% cases there is unilateral testicular involvement. Due to unilateral involvement and patchy interstitial inflammation, it is usually, not associated with sterility,
Grossly, The testis is enlarged with punctate hemorrhages in the tunica albuginea.
Microscopically, there are acute inflammatory cells together with infiltration of histiocytes in the interstitial tissue. Seminiferous tubules show no evidence of spermatogenesis and the cells in the lumen are Sertoli cells.
Neutrophils are usually not prominent but in the more intense inflammatory response, frank suppuration may develop with tubular lumen distended with pus.