[Facial myofibroma of the newborn simulating sarcoma]

Myofibromatosis is a rare but probably under estimated tumor.

We report a case of a newborn presenting with a facial tumor suggestive of sarcoma. Discrepancy between clinical features and histologic pattern of angioma suggested the diagnosis of myofibroma. The diagnostic of myofibromatosis was made later by specific labelling (actin-smooth muscle) and was confirmed by major spontaneous involution.

The histology of myofibroma associates fibrous and angiomatous patterns that may be confusing when examining a small biopsy. Due to confusing semiology and histology, subcutaneous myofibromas are certainly misdiagnosed and specific actin labelling (actin, HHF 35) may be of interest. Myofibromas are the most frequent tumor among fibromatoses. The diagnosis should be suspected on the stony consistence of the tumor uncompatible with angiomatous histology. Contrary to multicentric myofibromas of which the prognosis depends on visceral involvement and compressions (72 p. 100 of fatal outcome), solitary subcutaneous myofibroma has a very good prognosis with spontaneous involution.