Fibrous hamartoma of infancy with peripheral neuropathy in an adolescent: an exceptional clinicopathological presentation and review of literature

Fibrous Hamartoma of Infancy (FHI) is a rare benign fibroproliferative soft tissue tumor predominantly affecting infants and young children. First described by R.D. Reye in 1956 and subsequently characterized by Enzinger in 1965, FHI is defined by its distinctive triphasic organoid architecture comprising mature adipose tissue, fibrocollagenous trabeculae, and immature primitive mesenchymal tissue. Despite its characteristic histopathological appearance, FHI remains an underrecognized and diagnostically challenging entity because of nonspecific clinical, radiological, and cytological findings. Fewer than 200 cases have been documented in the English literature to date, with only sporadic reports from developing countries and the Indian subcontinent.This review summarizes the current understanding of FHI with emphasis on epidemiology, clinical presentation, radiological findings, cytological features, histopathological spectrum, differential diagnosis, immunohistochemical profile, molecular alterations, treatment, and prognosis. Histopathological examination remains the gold standard for diagnosis because of the characteristic triphasic morphology. Although immunohistochemistry has limited routine diagnostic utility, it may assist in excluding histological mimics and identifying atypical or malignant areas. Recent molecular studies demonstrating EGFR exon 20 insertion/duplication, ETV6 rearrangements, and PDGFB alterations suggest a possible neoplastic molecular basis for FHI. Complete surgical excision remains the treatment of choice, with recurrence usually related to incomplete excision and malignant transformation being exceedingly rare.