Lipoblastoma/lipoblastomatosis: a clinicopathologic study of 25 tumors.

Lipoblastoma/lipoblastomatosis is an uncommon benign adipose tissue tumor of children. Since 1958, 25 of these tumors from 24 patients have been reviewed in the Department of Pathology at The Children's Hospital of Philadelphia. Tumors were resected from 19 boys (79%) and five girls, and 20 patients (84%) were < or =5 years of age at diagnosis. Twenty-three tumors presented as painless superficial soft-tissue masses; one tumor was retroperitoneal and was discovered because of vomiting; one hand tumor was present at birth. Tumors occurred in an extremity (n = 11 patients), the head and neck (n = 5), groin (n = 2), axilla (n = 2), back (n = 1), chest (n = 1), flank (n = 1), labia (n = 1), and retroperitoneum (n = 1). Thirteen tumors occurred on the left side, and five occurred on the right. Lesions measured 1.0-21.0 cm in greatest dimension; 15 of 25 (60%) measured < or =5.0 cm. The largest (retroperitoneal) tumor weighed 450 g. Eleven tumors were discrete lipoblastoma, and 14 had irregular margins (lipoblastomatosis). Microscopically, the tumors displayed adipocytes in different stages of maturation; lobules bordered by septae that were cellular in 11 cases; prominent blood vessels in 19 cases; and myxoid foci in 13 cases. Chart review of 22 patients showed that one tumor recurred 4 years after resection; one tumor recurred after 7 years as fibrolipoma; and one incompletely resected tumor enlarged and at second resection was lipoma. There were no metastases. Three patients also had hemangioma. Juvenile aponeurotic fibroma occurred in one patient near the site of resection of a lipoblastoma 4 years earlier. We conclude that lipoblastoma/lipoblastomatosis behaves benignly, occurs in both superficial and deep sites, occasionally attains large size, may mature, can recur, and may be associated with other benign soft-tissue lesions. Complete surgical excision is the treatment of choice.