Congenital Mesenchymal Tumors

Abstract

The authors’ survey of 120 congenital mesenchymal tumors (37 cases of fibromatosis, 4 cases of fibrosarcoma, 15 cases of rhabdomyosarcoma, 17 cases of mesenchymoma, 13 cases of smooth muscle tumors, 11 cases of hemangiopericytoma, 2 cases of malignant hemangioendothelioma, 10 cases of histiocytic tumors, 3 cases of lipoblastic tumors, 2 cases of myxoma, and 6 cases of glomus tumors) emphasizes the rarity of truly malignant neoplasms of this type in the newborn. Certain tumors did not appear at all in malignant form, and other histologically malignant tumors behaved in a benign fashion. The only types known to have metastasized were rhabdomyosarcoma, malignant mesenchymoma and fibrosarcoma. Among the benign tumors only the fibromatoses were associated with significant morbidity or mortality and this is because the fibrous tissue either grew diffusely destroying an extremity or formed masses in vital organs. Forty tumors, about one-third of those surveyed, were histologically malignant. Nine of the 40 infants died of malignant tumor, 6 of these from rhabdomyosarcoma and one each of malignant mesenchymoma, fibrosarcoma and leiomyosarcoma of the prostate. There are too few cases available as yet for an understanding of the peculiarities of each type of congenital mesenchymal tumor. Our study emphasizes that congenital mesenchymal tumors rarely behave malignantly and suggests that congenital sarcomas differ biologically from those in the older age groups which they resemble histologically. The authors present summaries of sixteen cases from their collection of 120 cases of congenital mesenchymal tumors.