Retroperitoneal Lipoma in Children By Stanley Weitzner, Bernard I. Blumenthal. and Patricia C. Moynihan Jackson, Mississippi 9 A case of retroperitoneal lipoma in a 2 3 - m o old girl is reported together with a brief review of the 11 previously d o c u m e n t e d cases. It has been encountered through age 8 yr and t w i c e as frequently in girls. The majority had an enlarged abdomen of tong duration. The others w e r e asymptomatic and found incidentally or at the t i m e of examination for abdominal pain. M o s t lipomata were large. The possibility of their being congenital cannot be excluded. None have recurred. IN DEX W O R DS : Lipoma, retroperitoneal.

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SERIES of 190 cases of retroperitoneal tumors in infants and children, of which almost 90% were Wilms' tumor or neuroblastoma, included only two lipomata; no clinical i n f o r m a t i o n was provided for e i t h e r . ' In Kauffman and Stout's series of 8 children with lipoma, 7 were subcutaneous and 1 in the knee. Four of the subcutaneous lipomata were congenital. ~ H a r v a r d r e p o r t e d a case of retroperitoneal lipoma in a child and briefly reviewed those seven previously documented.:' T h r e e additional cases have since been reported. 4-6 The one case reported by Pinto et al. 7 is not included because histologically it was a liposarcoma. Of the eleven cases with clinicopathologic data, there were 4 boys and 7 girls aged through 8 yr. The majority had an enlarged abdomen of long duration (from 2.5 to 7 yr). Two of these children had abdominal pain which drew attention to this mass, but apparently was not d i r e c t l y r e l a t e d to it. Most of the r e t r o p e r i t o n e a l l i p o m a t a were large to voluminous, ranging to 20 c m i n diameter and up to 7.5 kg. None have been known to recur for periods up to 4.5 yr postoperatively.

From the Departments of Pathology, Radiology (Pediatric Radiology Division), and Surgery (Pediatric Surgery Division). Address reprint requests to Bernard 1. Blumenthal, M.D., Department of Radiology, University of Mississippi Medical Center, Jackson, Miss. 39216. 9 1979 by Grune & Stratton, Inc. 0022-3468/79/1401-0019501.00/0

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CASE REPORT A 23-mo-old girl was referred to the University of Mississippi Medical Center for evaluation of a right lower quadrant mass of several days' duration. The mother noted a lump in the child's right lower abdomen following a short bout of abdominal pain. She was previously asymptomatic and had no abnormal physical findings on routine checkups 2 wk earlier as well as at ages 6 wk and 6 too. The remarkable physical finding on admission was a 7 x 8 cm firm, nontender, nonmovable, nonpulsatile mass in the right lower quadrant. T h e inferior border of the mass, on rectal examination, was at the right pelvic brim. Routine clinical laboratory data were normal. A plain film of the abdomen revealed a well-demarcated, fat density mass in the lower and midright abdomen which on barium enema displaced the terminal ileum and right colon cephalad and anteriorly (Fig. 1).

Fig. 1. Barium enema, oblique view, showing a right retroperitoneal, well-demarcated, fat density mass with anterior and cephalad displacement of the terminal ileum and right colon.

Joumaf of Pediatric Surgery, Vol. 14, No. 1 (February), 1979

RETROPERITONEAL LIPOMA

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Fig. 2. Hemisection of lipoma homogenous, Iobulated cut surface.

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The radiologic diagnosis was right retroperitoneal lipomatous tumor. Chest x-ray and intravenous pyelogram were normal. There were no osseous abnormalities. At surgery, an encapsulated, lemon-sized, solid, yel[ow mass was dissected and removed from the right lower and mid retroperitoneal space. There was no apparent association with the right colon or kidney. The specimen consisted of an

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ovoid 6.5 x 5.5 x 4.8 cm, 190 g, encapsulated smooth surfaced, rubbery mass with a homogeneous, yellow lobulated cut surface (Fig. 2). It consisted microscopically of mature adipose tissue only (Fig. 3). Permanent sections confirmed the frozen section diagnosis of lipoma. The postoperative course was uneventful. She is well and without evidence of recurrence 1 yr later.

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WEITZNER, BLUMENTHAL, AND MOYNIHAN DISCUSSION

Lipoma may be distinguished on abdominal radiographic examination by its radiolucency and, thus, differentiated from the more common, dense appearing retroperitoneal neoplasms: neuroblastoma, Wilms' tumor, and soft tissue sarcomas. The lipomatous nature was recognized preoperatively in 2, 4 including the present case, of the 6 children 3-6 who had radiographic examination of the abdomen.

Whether lipoma of the retroperitoneum is congenital in children is conjectural, since an abdominal mass was not noted at birth in any of the cases. The presence, however, of an abdominal mass since early infancy in two, 3 indicates that their retroperitoneal lipoma was most probably congenital. In addition, the possibility that the retroperitoneal lipoma was present at birth, but too small to be recognized, cannot be definitely excluded in the others.

REFERENCES

1. Hastings N, Pollock WF, Synder W Jr: Retroperitoneal tumors in infants and children. Arch Surg 82:950 973, 1961 2. Kauffman SL, Stout AP: Lipoblastic tumors of children. Cancer 12:912-925, 1959 3. Harvard M: Retroperitoneal lipoma in children: Report of case and review of literature. J Urol 70:159-163, 1953

4. Seymour EQ, Puckette SE Jr: Retroperitoneal lipoma: A case report in an infant. J Urol 100:165 166, 1968 5. Wolk DP, Schuster KM: Retroperitoneal lipoma in a child. J Pediatr Surg 7:343-344, 1972 6. Gonzales ET Jr, Anderson EE: Retroperitoneal lipoblastic tumors in children. J Urol 110:474 475, 1973 7. Pinto VC, M a t t o s AG, Pimenta E, et al: Retroperitoneal myxolipoma; report of case in child 7 years of age. Pediatrics 14:11-15, 1954