Peripheral nerve biopsy: Is it still important for the early diagnosis of neural leprosy?

Background: The early recognition of neural impairment in leprosy represents a challenge in clinical practice and peripheral nerve biopsy may be required for diagnostic. Objective: Characterize the epidemiological, clinical, electroneuromyographic, laboratory and histopathological aspects of patients undergoing peripheral nerve biopsy during investigation of primary neural leprosy. Methods: 104 patients with peripheral neuropathy, referred to a national reference center leprosy, were biopsied. All patients had clinical evidence of peripheral neuropathy associated with the absence of skin lesions and were being investigated. Results: Of 104 biopsied, leprosy was confirmed in 89.4%. 66 were classified as primary neural leprosy and 27 as neural relapse or reinfection. All cases confirmed presented asymmetric neural impairment with predominance of sensory symptoms (88.2%), followed by muscular weakness and/or amyotrophy in 44.1% and pain in 34.4%. Neural thickening of one or more nerves was observed in 78.5% of the patients. The biopsied nerves were: ulnar (67.8%), superficial fibular (21.5%), sural (8.6%), radial (1.1%) and deep fibular (1.1%). 29% presented histopathological abnormalities and 4.4% acid fast bacilli. Nerve and superjacent skin qPCR were positive in 49.5% and 24.8% of cases, respectively. The patients with multiple mononeuropathy presented higher frequency of neural thickening (p<0.0001) and histopathological abnormalities (p=0.0077), but lower rates of positivity of ELISA anti-PGL-I (p=0.0100), qPCR in the peripheral blood (p=0.0157), and in the slit skin smear (p=0.0032). Conclusions: Peripheral nerve biopsy is an important tool in the investigation of primary neural cases, contributing to the early diagnosis and reducing diagnostic errors and the need for empirical treatment.