We report the case of a 42-year-old man whose only symptom was pain in the medial aspect of the left forearm. There were no paresthesiae and the clinical examination was normal except for the presence of a small lipoma at the elbow. Electromyographic examination confirmed the normality of the main nerve trunks of the left upper limb and demonstrated abnormalities of the left medial antebrachial cutaneous nerve when compared with the right side. On the basis of this finding, a local corticosteroid injection was performed, which rapidly and lastingly relieved the pain (no recurrence after 18 months).