Leprotic involvement of peripheral nerves in the absence of skin lesions. Case report and literature review.

In the absence of clinically apparent cutaneous lesions, primarily neural leprosy is uncommon. Primarily neural leprosy presents clinically as a peripheral neuropathy that most frequently affects motor nerves and that occasionally involves sensory nerves as well. The long incubation period for leprosy and its occurrence outside endemic areas often lead to delayed diagnosis. We present a case of glove and stocking hypoesthesia, weakness of the flexor muscle of the right great toe, palpable thickening of the right popliteal nerve, and hypoesthetic but normal-appearing areas on the back, which developed in a Trinidadian immigrant who lived in Canada for 16 years. A skin biopsy specimen obtained from a visibly normal but hypoesthetic area on the back demonstrated a few acid-fast bacteria in small dermal nerves, in arrector pili smooth muscle, and in rare perivascular histiocytes, associated with a sparse mixed inflammatory cell infiltrate. The patient responded well to therapy with dapsone, rifampin, and clofazamine. A classification and review of primarily neural leprosy is presented. Our patient represents the first reported case of primarily neural borderline lepromatous leprosy in Canada.