Fat necrosis mimicking liposarcoma in a patient with pelvic lipomatosis CT findings Nurten Andac ¸ a , Feyyaz Baltacıog ˇlu a, *, N C ¸ agatay C ¸ ims ¸it a , Davut Tu ¨ney a ,O ¨ zdemir Aktan b a Department of Radiology, School of Medicine, Marmara University, Istanbul, Turkey b Department of General Surgery, School of Medicine, Marmara University, Istanbul, Turkey Abstract Pelvic lipomatosis is a rare condition characterized by an overgrowth of normal fat in the perirectal and perivesical spaces. The most important differential diagnosis is liposarcoma. We present a case of pelvic lipomatosis associated with a mass, which was diagnosed radiologically as a liposarcoma, but surgical biopsy result revealed fat necrosis. D 2003 Elsevier Science Inc. All rights reserved. Keywords: Pelvic lipomatosis; Fat necrosis; CT; Liposarcoma 1. Introduction Pelvic lipomatosis is the nonmalignant proliferation of normal fat tissue in the perivesical and perirectal spaces. Although the exact incidence is unknown, it is reported in 0.6–1.7 cases per 100,000 hospital admissions between 1967 and 1975 in the USA [1]. The exact number is thought to be much higher since the diagnosis is very often not well recognized and thus missed by physicians. In this report, the radiological findings of a case of pelvic lipomatosis and fat necrosis mimicking liposarcoma, which has undergone CT examination for staging of gastric carcinoma, are discussed. 2. Case report Sixty-eight-year-old male patient with weight loss and epigastric fullness was reported to our clinic with an order for gastroscopy. The gastroscopy revealed a tumor in the corpus of the stomach and abdominopelvic CT was ordered for staging. The examination was performed with 7-mm slice thickness, with intravenous and oral contrast media. The mass lesion in the stomach was 45 Â 35 mm in size and invaded the perigastric fatty tissue. The lower abdomen contained fat tissue that filled the pelvis and extended into the abdomen. The mass effect caused by the fat tissue displaced the sigmoid colon to the left and the urinary bladder was elongating to the left side (Fig. 1A,B). Ileal loops were totally displaced to the left upper quadrant. Cecum was displaced to the upper right quadrant. A mass lesion 11 Â 10 Â 9 mm in size was noted in the right para- colic area, having a smooth contour and a fibrous capsule also with a fat density. The lesion showed mass effect on the right psoas muscle. Calcification was present in the wall of the fibrous capsule. There were linear densities in the fat tissue resembling fibrous bands. There was significant enhancement after intravenous contrast in the capsule that showed a solid component (Fig. 1C). The patient had a palliative operation for gastric carcinoma, and biopsies were taken from the pelvic fat tissue and encapsulated lesion in the same session. Pathological examination revealed mature fat cells in the pelvic fat tissue, and fat necrosis with hyalinated fibrous tissue and dystrophic calcifications was the result of the lesion in the right paracolic region. 3. Discussion Pelvic lipomatosis is a rare benign disorder described first by Engel in 1959 [2]. It is most frequent in the fourth 0899-7071/03/$ – see front matter D 2003 Elsevier Science Inc. All rights reserved. PII:S0899-7071(02)00519-3 * Corresponding author. Marmara U ¨ niversitesi Hastanesi, Radyoloji Anabilim Dali, 81190 Altunizade, Istanbul, Turkey. Tel.: +90-216- 3276955; fax: +90-216-3276956. E-mail address: fbaltaci@yahoo.com (F. Baltacıog ˇlu). Journal of Clinical Imaging 27 (2003) 109 – 111