MRI imaging of ulnar leprosy abscess.

Leprosy is a chronic granulomatous infection, caused by mycobacterium leprae, primarily affecting the peripheral nerve trunks and cutaneous nerves. It classically presents with neural or dermal signs and symptoms. The indolent course of leprosy may manifest as erythema nodosum (appearance of tender inflamed subcutaneous nodule) and reversal reaction (inflammation in the previous skin lesion, appearance of new skin lesions, neuritis and abscess). Ulnar nerve is most commonly involved. This report illustrates the MR imaging appearance of ulnar nerve abscess.