Fibrous hamartoma of infancy: Current review

This review examines 197 cases of fibrous hamartoma of infancy (FHI) descri bed in the Literature and provides a detailed clinicopathologic analysis of what is known to date of this peculiar lesion of the subcutis and lower de rmis. The vast majority of these cases occurred within the first year of li fe (91%). Twenty-three percent were congenital. There was a predilection fo r boys with a male/female ratio of 2.4. Males and females had similar anato mic distribution with the most common locations being the axillary region, upper arm, upper trunk, inguinal region, and external genital area. Most ca ses presented as solitary masses, but four cases of multiple separate synch ronous lesions have been reported. Most lesions presented as a painless nodule, sometimes with rapid growth. A few cases had overlying skin changes, including alteration in pigmentation , eccrine gland hyperplasia, and increased hair. No lesions were reported t o have familial or syndromic association, or to occur in combination with o ther hamartomas. Spontaneous regression has not been reported. The treatmen t of choice is local excision. Even with incomplete excision, FHI has a low recurrence rate. Criteria for histologic diagnosis include the presence of well-defined bundles of dense, uniform, fibrous connective tissue projecti ng into fat, primitive mesenchyme arranged in nests, concentric whorls or b ands, and mature adipose tissue intimately admired with the other component s. Flow-cytometric and conventional cytogenetic studies have not been reported ; these may clarify any relationship to other fibroblastic/myofibroblastic proliferations in children, resulting in better classification and terminol ogy of this unique lesion.