Leprosy can be difficult to diagnose, in particular the pure neuritic leprosy type. A 38-year-old male, former soldier and rural worker, presented with a 10-year history of supraclavicular and suprascapular hyperesthesia of the left side and progressive scapular left arm anesthesia, including the hand, associated with bone resorption in distal phalanges of the first and second finger. No typical leprosy skin changes were present. An examination of the skin revealed epitrochlear thickening of the left side cubital nerve, therefore primary neural leprosy was suspected. Skin smears from the routine sites were normal, as were two skin biopsies and the serologic assay specific for M leprae to detect phenolic glycolipid-1. Electromyography revealed an important reduction in the sensory action potential of the ulnar, radial and medial nerves, which favored the primary neural leprosy diagnosis. After two months of multibacillar leprosy treatment, the symptoms started to disappear and the patient could recommence his old job.
Pure neuritic leprosy presents with skin areas of hypesthesia and anesthaesia associated with nerve thickening. It is a disease that is commonly misdiagnosed for several years before the correct diagnosis is made and effective treatment is started. Electromyography can be a helpful tool in the diagnosis, typically showing reduced sensory action potential, while a biopsy of anesthetic skin is only helpful in one-third of cases. Reasonable clinical suspicion is sufficient to initiate antileprosy treatment when no other diagnostic methods are available.
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