DOI: 10.36347/sjmcr.2014.v02i10.008

Pages: 668-671

Lipomas are usually subcutaneous and asymptomatic. Rarely, they can occur in a deeper soft tissue plane exerting pressure on adjacent nerves. When adjacent to the neck of the radius, it can cause posterior interosseous nerve compression. The radial nerve originates from the posterior cord of the brachial plexus with contributions from C5, C6, C7, C8 and T1. It enters the forearm just deep to the brachioradialis muscle and bifurcates into superficial and deep branches. The superficial branch provides sensory innervation to the skin on the dorsolateral surface of the hand. The deep branch becomes the posterior interosseous nerve (PIN) after emerging between the two heads of the supinator muscle. It supplies motor innervation to the muscles in the posterior compartment of the forearm. First described in the literature by Richmond in 1953 lipomas of the proximal forearm are an uncommon cause of PIN compression. Patients with PIN palsy caused by compression from a lipoma typically describe weakness of digital extension evolving over a period of several months. To date, fewer than 40 cases have been reported in English literature. We present a case of PIN compression by lipoma in a 40-year-old female.