LEIOMYOSARCOMAS IN CHILDREN - CLINICAL AND PATHOLOGICAL CHARACTERISTICS

Leiomyosarcomas (LMS) are extremely rare in children, accounting for only 2% of their soft-tissue sarcomas [11]. We report our experience with nine children treated for LMS between 1962 and 1990. Their ages at diagnosis ranged from 1 day to 17 years (median 5 years); six were female and eight were Caucasian. Five tumors were stromal sarcomas originating in the gut (ileum 2, stomach 1, jejunum, sigmoid 1). Three were intra-abdominal tumors that originated in the retroperitoneum (2) and abdominal wall (1). In one patient the tumor appeared in the subcutis of the thigh. Operations were uniformly performed, resulting in complete resection of the tumor in six of nine cases. Five patients received adjuvant chemotherapy and one received radiation therapy only. Five patients were alive 6-38 months (median 16 months) after diagnosis. The remaining four died of their disease 4-27 months after diagnosis, three of locally recurrent disease and one of hepatic metastasis. Four of the six patients with complete resection were alive 6-27 months after diagnosis. Both patients with low-grade (grade I) sarcomas had complete resections and were alive 33-38 months after diagnosis. Clinical outcome correlated roughly with the mitotic rate of the tumors, as all three patients with mitotic count > 5/10 high power fields (HPF) died between 4 and 14 months after diagnosis. Immunohistochemical stains using the avidin-biotin-complex procedure on formalin-fixed tissue were performed for six tumors. Only muscle-specific actin (MSA) was uniformly positive (6/6). The other significant marker was desmin, which was positive in three tumors. Favorable outcome of LMS in children correlates best with low mitotic counts (< 5/10 HPF), low tumor grade, and complete surgical excision. Immunohistochemical analysis suggests that these tumors are of myogenic origin.