Soft tissue tumors in first year of life: a report of 190 cases.

A comprehensive review of soft tissue tumors in children and adolescents disclosed the presence of 190 neoplasms in 183 patients, which were diagnosed in infants between birth and 12 months of age; these infants represented approximately 20% of our entire pediatric soft tissue tumor series. In excess of 75% of cases were pathologically benign with the hemangioendothelioma, lymphangioma, and fibromatosis-myofibromatosis constituting the majority of cases in this category. Fibrous histiocytoma and lipoblastoma were the other two benign entities. Congenital-infantile fibrosarcoma was considered a borderline tumor because of its infrequently manifested potential for metastasis; none of the 13 cases in the present study behaved in a malignant fashion. Embryonal rhabdomyosarcoma and peripheral primitive neuroectodermal tumor were the two principal types (17 of 27 cases) of malignant soft tissue tumors. In contrast to soft tissue tumors in the first two decades, those in the first year of life were more often benign despite their cellularity and presence of mitotic activity. Fibroblastic-myofibroblastic tumors were more frequent in this young age group, whereas neurogenic and myogenic tumors were relatively more common in children older than 1 year of age. The trunk and head and neck region were the preferred topographic sites rather than the extremities, which was the case in children beyond the first year of life.