Granulomatous (Autoimmune) Orchitis:
Granulomatous orchitis is an uncommon cause of unilateral testicular enlargement in middle-aged men. It has a possible autoimmune origin.
Clinically, most cases present with sudden onset of tender testicular mass, sometimes associated with fever. It may be painless in some patients and difficult to distinguish from testicular neoplasia.
Microscopically, non-caseating granulomas occur within testicular tubules and adjacent connective tissue, accompanied by occasional plasma cells and neutrophils.
Epithelioid cells may originate from Sertoli cells.
Lesions must be differentiated from granulomas of tuberculosis.
Grossly, the testis is enlarged, grayish-white or brownish in colour with normal or thickened tunica albuginea.