Laurent Wehrli MD, Abstract Co-Author: Nothing to Disclose

Monica Khanna MBBS, FRCR, Presenter: Nothing to Disclose

Matthew Lax MD, Abstract Co-Author: Nothing to Disclose

Dimitri Anastakis MD, Abstract Co-Author: Nothing to Disclose

To determine the incidence and pattern of brachial plexus involvement in confirmed cases of distal focal lipofibromatous hamartoma (LFH) of the upper limb using MR imaging.

7 patients (age 30-64 yrs, 3F; 4M) with clinical and MRI diagnosis of LFH of the upper limb were recruited from the hand surgery unit. 8 upper extremities (1 patient with bilateral LFH) were imaged from the MCP joints to the brachial plexus using a GE Signa 1.5-T system with axial and coronal acquisitions. The brachial plexus was imaged in the coronal, sagittal and axial planes. T1-W and T2-W fat-saturated sequences were acquired. The brachial plexus and its distal branches were evaluated for thickened nerve fascicles. The extent of longitudinal nerve involvement, maximal cross sectional enlargement and the presence of surrounding fat distribution was documented. Magnetic resonance imaging of the spinal cord and brain was performed in patients with brachial plexus involvement to evaluate for associated central nervous system pathology.  

5 of 8 (62.5%) limbs demonstrated proximal brachial plexus involvement with thickening of the C7, C8 and T1 nerve roots with trunk, division and cord involvement and increased intervening fat signal. 2 had discontinuous LFH of the median and ulnar nerves, 1 had continuous LFH of the ulnar nerve and 1 had LFH of the median, ulnar, radial and axillary nerves, with continuous involvement of the ulnar nerve. 1 had continous involvement of the ulnar, median and radial nerve and a type II Arnold-Chiari malformation, which is not an established association. All patients with brachial plexus involvement had ulnar nerve involvement. 3 patients had normal brachial plexus imaging with LFH isolated to the median nerve distal to the proximal margin of pronator quadratus.    

LFH should not be considered a simple distal focal nerve pathology. Brachial plexus abnormality is common (62.5%) in our cohort of patients with fibrolipomatous hamartoma of the upper limb involving multiple nerves or a single continuous nerve. Ulnar nerve involvment was always associated with brachial plexus involvement. Chiari type II malformation was present in 1 patient.  

Brachial plexus MR has a role in the diagnostic work-up of LFH patients, especially in patients with ulnar nerve abnormalities. We advice an MR of entire limb and CNS when the ulnar nerve is affected.

Wehrli, L, Khanna, M, Lax, M, Anastakis, D, Lipofibromatous Hamartoma: Magnetic Resonance Imaging of the Brachial Plexus and Central Nervous System.  Radiological Society of North America 2010 Scientific Assembly and Annual Meeting, November 28 - December 3, 2010 ,Chicago IL. http://archive.rsna.org/2010/9005833.html