An unusual cause of shoulder pain

A 20 year old man with no significant past medical problems presented with a six week history of gradual onset diffuse left shoulder and scapula pain. Two weeks before the onset of pain he had started work as a builder, performing heavy lifting. There was no history of injury or other precipitant. In the week before presenting, the severity of the pain prevented him from working despite regular analgesia. He did not complain of upper limb weakness. No constitutional symptoms were present. There was no preceding viral-like illness or vaccination. On examination, there was left infraspinatus tenderness and wasting (see fig 1) with weakness of external rotation of the shoulder. Power in other muscle groups around the left shoulder was normal. All upper limb reflexes were present and sensation was normal. Examination of the left axilla revealed five small mobile lymph nodes. There was no other lymphadenopathy or splenomegaly. Figure 1 Left infraspinatus wasting. (View from behind the patient). Computed tomography (CT) of the left scapula and axilla was performed to determine if significant lymphadenopathy was present, for example, because of lymphomatous involvement. It showed wasting of the muscles surrounding the scapula but no mass lesions in the region of the brachial plexus. There were non-enlarged lymph nodes in the axilla. Electromyographic (EMG) assessment revealed profuse fibrillations and positive sharp waves …