Retroperitoneal fat necrosis producing ureteral obstruction

Area of Science:

• Nephrology
• Urology
• Pathology

Background:

• Idiopathic retroperitoneal fibrosis is a known cause of ureteral obstruction.
• Retroperitoneal fat necrosis is a rare condition with unclear etiology.

Observation:

• Three cases of extrinsic ureteral obstruction due to retroperitoneal fat necrosis were identified.
• Clinical presentation showed similarities to idiopathic retroperitoneal fibrosis, including age, sex, pain, elevated blood urea, and bilateral involvement.
• Two of the three cases had a history of ischiorectal abscess.

Findings:

• Histopathology of retroperitoneal fat necrosis revealed fat cysts with granulomas and minimal fibrosis.
• Idiopathic retroperitoneal fibrosis showed dense collagenized fibrous tissue without fat necrosis.
• Distinct histological differences were observed between the two conditions.

Implications:

• Retroperitoneal fat necrosis is a distinct entity that can mimic idiopathic retroperitoneal fibrosis clinically.
• Understanding the etiology, potentially linked to abscesses, is crucial for managing this rare cause of ureteral compression.
• Further research is needed to elucidate the pathogenesis of retroperitoneal fat necrosis.