Emphysematous epididymo-orchitis

Emphysematous epididymo-orchitis is a rare gas-forming epididymo-orchitis. The pathology of this condition is unknown. The diagnosis is usually made by ultrasonography with CT as an adjunct, to confirm the diagnosis, evaluate its extent and to rule out a coexistent retroperitoneal infective focus. It has a high mortality rate and usually necessitates emergent orchiectomy.

Clinical presentation

All case reports describe spontaneous 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, leukocytosis, pyuria (pus in the urine) and bacteriuria.  

Pathology

Pathology of this entity is unknown with diabetes mellitus being a key predisposing factor in most cases (as for 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 artifacts 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 bodies. The presence of posterior dirty shadowing, reverberation artifacts and clinical profile help differentiate these entities. There may be an associated reactive hydrocele, funiculitis and scrotal wall thickening with increased vascularity.

CT

CT is the modality of choice to demonstrate intratesticular gas. Hypodense foci or patchy areas (~ -1000 HU) 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 diverticula and retroperitoneal emphysematous infections.

MRI

MRI can confirm the presence of gas 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 orchiectomy.

Treatment and prognosis

Time is the key to successful management. Emergent orchiectomy is the treatment of choice with secondary management of predisposing conditions like retroperitoneal infection or sigmoid diverticula. Good glycemic control in the context of diabetes mellitus may help prevent the condition.

Differential diagnosis

• Fournier gangrene with testicular involvement 
  • presence of gas within the subcutaneous plane with necrotizing 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)