Clinical, histopathological and differential diagnostic features of an infantile myofibromatosis case which is uncommon and can be confused with malignancies, is presented. A fourty five-day-old male baby was brought to Department of Pediatrics of Gulhane Military Medical Academy by his mother with the complaint of swellings in different sites of his body. Nodular lesions were seen on his chest and foot. The lesion on the chest and one of two lesions on the foot were totally excised in Department of Pediatric Surgery of Gulhane Military Medical Academy. Macroscopically, specimens consist of two gray-white coloured nodular tissues which are measured 1,5 and 0,7 cm in diameter. In histopathological examination, cutaneous and subcutaneous localized tumoral lesions which contain hypocellular-hypercellular areas showing nodular pattern were detected. Hypocellular areas consist of myoid cells which create short fascicles and whorl like structures. Hypercellular areas consist of round-polygonal cells and spindle cells which create hemangiopericytoma like structures in some areas. It was detected that five-six mitotic figures in ten high magnification fields with expressions of aktin and vimentin immunohistochemically in neoplastic cells. According to these findings, lesions were reported as infantile myofibromatosis. Since there was no systemic involvement, it was decided to follow up the patient without an additional treatment.

Infantile myofibromatosis can be reported as a malignant lesion because it shows high mitotic activity. However, if the lesion is restricted solely in cutaneous- subcutaneous tissues and bone, prognosis is very excellent. Generally, surgical interventions which are performed for diagnosis are sufficient. Lesions generally regress spontaneously in one year. If visseral organs are involved prognosis is poor.

Keywords: Infantile Myofibromatosis, Cutaneous and Subcutaneous Tissues