Leiomyosarcomas in childhood: a clinical and pathologic study of 10 cases.

Ten children (5 males, 5 females) with leiomyosarcomas were treated at the Children's Hospital, Boston, during the 20-year period from 1963 through 1983. The patients ranged in age from 2 1/2 to 15 years, the average age at diagnosis being 10 1/2 years. The tumors originated in the following sites: stomach (4 cases), jejunum, cecum, endocervix, retroperitoneum, urinary bladder, and base of tongue (1 case each). In each case the primary tumor was surgically resectable, with the average diameter being 6.7 cm (range 2-11 cm). The tumor proved fatal for 3 of 6 children with regional or distant metastases. Three others were alive with metastatic leiomyosarcoma 6-18 years following diagnosis. A fourth death was attributed to a massive chondrosarcoma of the lumbosacral area, which developed 7 years after hysterectomy, chemotherapy, and radiation therapy for an endocervical leiomyosarcoma. While leiomyosarcomas are extremely rare in the pediatric age group (less than 2% of all soft tissue sarcomas), diagnostic features and biologic behavior appear similar to those in adults. Tumor size and mitotic counts seem to be the most important features in assessing malignant potential, but absolute minimum criteria for malignancy are not well defined.