Retroperitoneal Fat Necrosis in a Patient with Extensive Weight Loss After Adrenalectomy for ACTH-Independent Cushing Syndrome: A Case Report and Review of the Literature

ABSTRACT Objective: To report a case of retroperitoneal fat necrosis (RFN) found after extensive weight loss following left adrenalectomy in a woman with Cushing syndrome. Methods: Case-based review of RFN without pancreatic disorders. We performed a PubMed search using the search term ‘retroperitoneal fat necrosis.’ Results: A 33-year-old woman with Cushing syndrome developed bilateral fat-containing infiltrative soft-tissue neoplasms in the perinephric space, measuring 5.0 × 7.5 cm (right) and 7.8 × 8.1 cm (left), with numerous enlarged retroperitoneal lymph nodes and fat stranding, 10 months post–left adrenalectomy for a 9-cm adrenal cortical neoplasm of uncertain malignant potential. Both computed tomography (CT)-guided core-needle biopsy followed by exploratory laparotomy with biopsy of the retroperitoneal masses showed that it was fat necrosis (FN) surrounded by a narrow rim of fibrous tissue with chronic inflammation. No further intervention was initiated, and CT abdomen 27-months postsurgery demonstrated reduction in both masses to 0.8 × 2.4cm (right) and 1.5 × 4 cm (left), with resolution of the lymphadenopathy. Conclusion: RFN not associated with pancreatic disorders is rare, and only 5 cases have been reported in the literature. FN is a benign inflammatory process that can mimic the features of a malignant mass and almost always, a biopsy may be required for a definitive diagnosis. FN associated with significant weight loss following unilateral adrenalectomy for Cushing syndrome has not been reported in the literature. FN should be considered in the differential diagnosis of a mass appearing in an obese patient with substantial weight loss after surgery. Abbreviations: CT = computed tomography; FN = fat necrosis; HPE = histopathologic exam; RFNWP = retroperitoneal fat necrosis without pancreatic disorders