Fibrolipomatous Hamartoma of the Median Nerve Misdiagnosed as a Palmar Space Abscess: A Case Report.

Background: Fibrolipomatous hamartoma (FLH), also categorized under lipomatosis of nerve, is a rare, is an uncommon benign fibrofatty lesion of the peripheral nerves that most commonly affects the median nerve. Its slow progression and atypical presentation often lead to misdiagnoses and improper surgical management. Case Presentation: A 17-year-old female presented with a 5-year history of progressive left-hand swelling and paraesthesia and a 2-year history of pain and secondary reduction in grip strength. The mass was previously misdiagnosed as an acute mid-palmar space abscess, which resulted in an ineffective incision and drainage. Magnetic Resonance Imaging (MRI) revealed severe median nerve enlargement with pathognomonic "coaxial cable" (axial) and "spaghetti-like" (coronal) patterns. To prevent neurological deficits, a biopsy was avoided, and the patient underwent open carpal tunnel decompression. At 6-month postoperative follow-up, she demonstrated substantial symptomatic relief, restoration of pain-free grip and pinch strength, and no signs of neurological deterioration. Conclusion: FLH can mimic common inflammatory or infectious hand masses. Magnetic resonance imaging (MRI) provides highly characteristic features that allow a clinicoradiological diagnosis, generally obviating the need for an invasive biopsy. Carpal tunnel decompression may provide symptomatic relief in patients with compressive neuropathy while avoiding potentially injurious intraneural resection.