Lipofibromatous Hamartoma of the Median Nerve: A Case Report

Abstract

Lipofibromatous hamartoma is a rare and slow growing benign fibro-fatty tumor. It is characterized by the proliferation of mature adipocytes within the epineurium and the perineurium of the peripheral nerves. In the upper extremity, it most commonly affects the median nerve. Median nerve involvement commonly leads to pain, numbness, paresthesia and carpal tunnel syndrome. This article presents a case of lipofibromatous hamartoma in an 8-year-old child followed by a discussion of the epidemiology, diagnosis, imaging details and treatment options for this condition.

Keywords: Carpal tunnel; Case report; Fibrolipoma; Fibrolipomatous hamartoma; Hamartoma; Intraneural lipoma; Lipofibroma; Lipofibromatous hamartoma; Macrodactyly; Magnetic resonance imaging; Median nerve; Microdystrophia lipomatosa; Perineurolipoma.

Figure 1

8-year-old male with LFH of the median nerve. FINDINGS: Initial frontal (A) and lateral (B) radiographs demonstrate enlargement of thenar eminence of right hand (white arrow). The actual substance of the LFH is not visible by plain radiography. TECHNIQUE: Frontal and lateral radiographs of the right hand.

Figure 2

8-year-old male with LFH of the median nerve. FINDINGS: (A) and (B) are axial T1-weighted images through the distal forearm and mid-hand respectively. The intrinsically T1-hyperintense fat surrounds and separates the T1-hypointense nerve bundles; the LFH mass, which measures 1 × 2 × 12 cm in total, is circled. (C) Proton density fat-suppressed (PDFS) axial image; the fatty substance of the mass here suppresses and the nerve bundles are visible as slightly hyperintense dots (arrow). (D) Sagittal T1-weighted image shows the fatty LFH with cable-like T1-hypointense nerve bundles (black arrow). A white arrow depicts the point of compression as the mass passes through the carpal tunnel. (E) Sagittal T1-weighted image with white arrows demarcating the palmar border of the LFH. TECHNIQUE: 3 Tesla non-contrast MR imaging of the right wrist with a quad knee coil with FOV=17 cm and slice thickness of 2 mm. T1-weighted imaging with TR=783 and TE=9. PDFS imaging with TR=3050 and TE=50.

Figure 3

8-year-old male with LFH of the median nerve. FINDINGS: Repeat non-contrast MRI obtained 11 months later in the same patient demonstrating interval growth. (A)-(C) T1-weighted axial, coronal, and sagittal images respectively with arrows delineating the borders (white arrows) of the LFH - which is larger in cross-sectional area than on prior examination. The T1-hypointense coaxial-cable-like nerve bundles are contained within the fatty-substance of the LFH. TECHNIQUE: 3 Tesla non-contrast MR imaging of the right wrist was performed with a quad knee coil with FOV=17 cm and slice thickness of 2 mm. T1-weighted imaging was performed with TR=783 and TE=9