Abstract

Lipomas are discrete and encapsulated benign tumors which usually involve head, neck, shoulder trunk, lower and upper extremities. However, lipomatosis is a more diffuse fatty tissue growth. A 34 year-old male was presented with a painless abdominal mass and diffuse lipomatosis that involving the peritoneum, retro-peritoneum and abdominal wall. The disease was noticed during the first year of his life as masses in the axillary fossa. Later the disease presented as multi-focal diffuse lipomatosis synchronously involving the intra-peritoneum and retro-peritoneum which is a rare pattern of involvement as in as few cases previously reported in the literature. Radiological evaluation revealed extension into the abdominal organs and structures. Interestingly, all lesions showed high FDG uptake on PET/CT scan, although lipomas do not take up FDG contrary to liposarcomas. The patient was operated many times and the pathological evaluations of all excised samples from the intra and retroperitoneum were consistent with mature lipid tissue. The FDG hypermetabolism on PET/CT scan was attributed to possible aggressive nature of the disease even if it was histopathologically benign. Non-invasive management instead of extensive surgical approach was considered for the patient with asymptomatic disease because of the possible high rates of morbidity and mortality which would be caused by extensive excision.