A case of infantile digital fibromatosis with spontaneous regression.

We reported a fourteen-month-old boy with infantile digital fibromatosis. At the age of seven months, a nodule appeared on the back of the left third toe, and developed into a slight red tumor divided into five hemispherical nodules. Histopathologically, spindle-shaped tumor cells with an eosinophilic inclusion body in the cytoplasm were seen in the dermis. Electron microscopy showed a dense body in the cytoplasm of the tumor cells. One year and two months after the first visit, the tumor regressed without any aggressive treatment. Japanese cases of infantile digital fibromatosis were reviewed. The literature review and our case suggest that the tumor should be observed without any aggressive treatment unless it causes mobile dysfunction of the affected finger or toe.