[Fibrous hamartoma in childhood].

Is a rare soft tissue benign tumor usually appearing during the first two years of life, often occurring in axillary or upper arm region subcutaneous tissue. Surgery is the treatment of choice. The lesion histologically consists of three different tissue elements: dense mature fibrocollagenous, loose immature myxoid mesenchymal and mature adipose tissue. A case of fibrous hamartoma of infancy with the usual clinical characteristics, but with particular microscopic features due to the abundance in fibrocollagenous and scarcity of myxoid tissue, is described. The results of the immunohistochemical and ultrastructural study on the same patient are reported. The differential diagnostic problems are discussed.