INFANTILE DIGITAL FIBROMATOSIS - A STUDY OF THE DEVELOPMENT AND REGRESSION OF CYTOPLASMIC INCLUSION-BODIES

An 8-yr-old Japanese boy developed infantile digital fibromatosis in t he right ring finger with recurrence and another lesion in the right m iddle finger. Histologic investigation of the tumor disclosed that the size and frequency of inclusion bodies were inversely proportional to the degree of fibrosis. Electron microscopic study revealed a variety of stages in the development of inclusion bodies, ranging from small, dense aggregates of filaments into bundles with dense bodies traversi ng the cytoplasm to typical inclusion bodies that also contained cytop lasmic organelles. In areas of dense fibrosis, the cytoplasm of the tu mor cells showed areas of constriction and compression by adjacent bun dles of collagen. The tendency for a decrease in the number of inclusi on bodies in these areas necessitated a differential diagnosis from ot her fibrous or fibro-histiocytic lesions. Our findings suggest that th e tumor may undergo a decrease in the numbers of inclusion bodies and spontaneously may become fibrotic with time. Thus, even as a form of f ibromatosis featuring both recurrence and multiple lesions, it may not have a consistently aggressive nature. These findings support the con cept that infantile digital fibromatosis should be managed by limited excision rather than by immediate aggressive surgical treatment.