Visibly Enlarged Feeder Nerves in Hansen's Disease: A Diagnostic Beacon

A 68-year-old male presented with asymmetric anesthetized erythematous annular large plaques on the anterior and medial aspect of right and left thighs for 3 years (Figure 1a,b). The lesions were non-tender and did not show any signs of inflammation. On examination, the right ulnar nerve and common peroneal nerves were enlarged and there was decreased sensation in the distribution areas of these nerves. Enlarged nerves were visible on the skin adjacent to the lesions on both thighs (Figure 1b,c). There were no deformities in the limbs. The patient had a Grade 1 disability as per the WHO disability grading. A slit skin smear was negative. Histopathology showed numerous granulomas with perineuro distribution (Figure 2a,b). The patient was diagnosed with borderline tuberculoid leprosy. Enlargement of peripheral nerves in leprosy is common, but the enlarged cutaneous nerves are rarely visible in tuberculoid and borderline tuberculoid leprosy [1]. Mycobacterium leprae is a neurotrophic bacillus. The mechanism of thickened cutaneous nerves in leprosy can be explained by ascending neuritis starting at the distal ends of cutaneous nerves from an infected skin lesion [2]. Sunil Jaiswal: conceptualization (lead), writing – original draft (lead), writing – review and editing (lead). Shraddha Uprety: investigation (lead), writing – original draft (lead). Pratichya Thapa: conceptualization (lead), methodology (lead). Prakriti Lamichhane: methodology (lead), conceptualization (supporting). All the authors contributed equally. The authors sincerely thank Prof. Dr. Sushna Maharjan, Head of the Department, Department of Pathology, Chitwan Medical College, for the expert histopathological analysis and valuable insights in diagnosing this case. Patients in this manuscript have given written informed consent for participation in the study and the use of their de-identified, anonymized, aggregated data and their case details (including photographs) for publication. Ethical approval is not applicable. The authors declare no conflicts of interest. The data that support the findings of this study are available from the corresponding author upon reasonable request.