Recurrent digital fibromatosis of childhood. An ultrastructural and immunohistochemical study of two cases.

Two cases of recurrent digital fibromatosis of childhood were studied by electron microscopy and immunohistochemistry, using rabbit anti-actin antisera. The tumor cells were typical myofibroblasts, containing inclusion bodies and bundles of microfilaments. Immunohistochemistry showed the presence of actin in these cells, thus proving the myofibroblastic nature of the tumors. Inclusions were negative or showed a weak annular positivity. A possible explanation of these findings is discussed.