Fibrous hamartoma of infancy in the lumbosacral region: A case report of a rare soft-tissue tumor.

Background: Fibrous hamartoma of Infancy (FHI) is a rare, benign mesenchymal lesion typically presenting within the first 2 years of life. While it commonly occurs in the axilla, shoulder, or upper trunk, lumbosacral involvement is exceptionally rare and can mimic other congenital or neoplastic lesions, leading to diagnostic difficulty. Case Description: We report a 10-month-old male infant with a 7-month history of a progressively enlarging midline lumbosacral mass. The swelling, measuring 15 × 13 cm, was soft, non-tender, and had ill-defined margins. Initial ultrasonography was inconclusive. Magnetic resonance imaging (MRI) of the spine showed a heterogeneous subcutaneous lesion without spinal cord involvement. Complete excision biopsy was performed, and histopathology confirmed the diagnosis of FHI, showing the characteristic triphasic pattern of mature adipose tissue, fibrocollagenous stroma, and immature mesenchymal elements. The postoperative course was uneventful, and the patient remains well at 2 months of follow-up with no evidence of recurrence. Conclusion: Lumbosacral FHI is exceedingly rare and diagnostically challenging, usually requiring MRI for lesion delineation and histopathology for definitive diagnosis. Prognosis is excellent following complete surgical excision. A high index of suspicion is essential to avoid misdiagnosis and unnecessary intervention. In low-resource settings, structural and economic barriers may significantly delay access to appropriate care. Strengthening healthcare infrastructure and improving diagnostic pathways are essential to ensure timely management and good clinical outcomes.