Leprotic involvement of peripheral nerves in the absence of skin lesions

In the absence of clinically apparent cutaneous lesions, purely neural involvement in leprosy is uncommon. These are recognized as pure neural leprosy and can be seen in 4 to 10% of leprosy patients. Primarily neural leprosy presents clinically as peripheral neuropathy that most frequently affects motor nerves and occasionally sensory nerves as well. Since its involvement is patchy, most of the time, histology is not supportive.

We present a 17-year-old boy with glove and stocking hypoesthesia, intrinsic muscle wasting of hands and bilateral ulnar claw hand. There was no thickening of superficial nerves. Sural nerve biopsy was performed and histology revealed inflammatory infiltration and presence of Mycobacterium leprae.

We believe that in cases of peripheral neuropathy without a known aetiology, it is useful to perform a superficial nerve biopsy to exclude the diagnosis of pure neural leprosy mainly in developing countries where leprosy is prevalent.

This case is reported as pure neural leprosy is uncommon and the yield of positive histology with numerous Mycobacterium leprae is very rare.