Emphysematous epididymo-orchitis

Emphysematous epididymo-orchitis is a rarely reported entity with only a handful of case reports. It is reported as a rare cause of acute scrotum encountered in poorly controlled diabetics. The pathology of this condition is unknown with few possible hypotheses postulated. The diagnosis is usually made by ultrasonography with CT acquired to confirm the diagnosis, evaluate the extent of emphysematous spread of infection and to rule out coexistent retroperitoneal source. It carries a high mortality rate and requires emergent orchidectomy.

Clinical presentation

All case reports published described a spontaneous presentation of sudden onset testicular pain which does not relieve with scrotal elevation. It is associated with local inflammation, i.e. swelling, reddening and local rise in temperature. There may be associated fever, leucocytosis, pyuria and bacteriuria.  

Pathology

Pathology of this entity is unknown with diabetes mellitus being a predisposing factor as with other emphysematous infections. The following hypotheses are postulated:

• coexistent retroperitoneal emphysematous infection adjacent to the origin of the testicular artery with involvement of the ipsilateral testis
• rupture of sigmoid diverticula into the seminal vesicle as a source of air within the testis

Radiographic features

Ultrasonography

Hyperechoic foci within the testicular parenchyma showing posterior dirty shadowing and reverberation artefactsartifacts or a curved hyperechoic line conforming to the globular shape of testis is seen on high resolution ultrasound of scrotum suggesting the diagnosis. This hyperechogenicity needs to be differentiated from testicular microliths, sutures and foreign body. The presence of posterior dirty shadowing, reverberation artefactsartifacts and clinical profile help differentiate these entities.  ThereThere may be an associated reactive hydrocoele, funiculitis and scrotal wall thickening with increased vascularity.

CT

CT is the modality of choice to demonstrate intratesticular air. Hypodense foci or patchy areas (Hounsfield unit value around -1000) noted within the testicular parenchyma confirm the diagnosis. CT also helps in determining the extent of spread of infection. The images may also point toward other associated conditions like sigmoid diverticulae and retroperitoneal emphysematous infections.

MRI

MRI can confirm the presence of air within the testis but is time consuming and does not add any further to the diagnosis. Thus MRI in these cases is not recommended as it delays the emergent orchidectomy.

Treatment and prognosis

Time is the key to successful management. Emergent orchidectomy is the treatment of choice with secondary management of predisposing condition like retroperitoneal infection or sigmoid diverticulae. Strict control of diabetes may help prevent this condition. The prognosis is usually worse.

Differential diagnosis

Fournier gangrene with testicular involvement: Differentiation between emphysematous epididymo-orchitis and Fournier gangrene with testicular involvement is a challenge even radiologically. Presence of air within the subcutaneous plane with necrotising fasciitis of perineal, genital and perianal regions point towards this entity. This is rarely reported with such cases having a retroperitoneal source of infection highlighting the difference in arterial supply of the testis (testicular artery from aorta) and scrotal wall (branches from internal iliac artery).