Granulomatous Orchitis, Idiopathic
Idiopathic granulomatous orchitis is an uncommon inflammatory testicular lesion that follows a gram negative urinary tract infection in the majority of cases. It is most prevalent in the 5th and 6th decades. Testicular involvement is usually diffuse but may also present as a localized nodular lesion and may simulate a testicular neoplasm. The epididymis and spermatic cord may also be involved.

The inflammatory process is predominantly intratubular with the cellular infiltrate containing a majority of histiocytes admixed with lymphocytes and plasma cells. Giant cells may also be present.  The predominance of histiocytes imparts a granulomatous appearance but distinct granulomas are not formed.  Non-specific chronic interstitial inflammation is also a feature of this condition.

The intratubular localization of inflammation in granulomatous orchitis aids in its distinction from infectious granulomas (mycobacterial, leprosy, brucellosis etc.) and sarcoidosis which are predominantly interstitial processes. Necrosis is not seen in granulomatous orchitis. Failure to correctly identify sperm that stain positive with acid fast stains could lead to misdiagnosis of mycobacterial infection.
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