Primary peritoneal, omental, and mesenteric tumors in childhood.

Of 21 primary peritoneal, omental, and mesenteric tumors, 14 were cysts and seven were solid. Most of the cysts were omental-mesenteric lymphangiomas; the sole exception was a cystic mesothelioma in a newborn. The solid tumors included three multicentric hamartomas, three sarcomas of undetermined histogenesis, and one immature teratoma. Since cystic lymphangiomas carry a good prognosis following surgical excision, they must be distinguished from cysts of mesothelial origin. Solid hamartomas may simulate malignant tumors because of multicentricity and immature tissue composition. Although peritoneal sarcomas of undetermined histogenesis are apt to be large, composed of primitive cells, and disposed to the development of implants, current treatment modalities may control the disease. One of three treated patients survived for 8 years. A child with a solid immature teratoma without a malignant germ-cell component remains free of disease 5 years after diagnosis. Our review, which represents the combined experience of two children's hospitals over several decades, did not include tumors such as malignant mesothelioma, lipoma, liposarcoma, leiomyoma, mesenchymoma, fibromatosis, and other neoplasms, which may rarely arise in the peritoneum, omentum, and mesentery of children.