Introduction: Pure neural leprosy (PNL) is characterized by the absence of skin lesions and negative slit skin smear, however, several studies found that up to 35% cases will progressed to visible skin lesion.
Case: A 62-year-old man came with chief complaint of facial edema, wound, and deformities. The nerve impairment and deformities started progressively seven years ago, followed by the emergence of skin lesion recently. Clinical examination revealed madarosis, earlobes infiltrate, punched-out lesion on the face, hypopigmentation on the truncus and extremities with sensory impairment, nerve enlargement alongside sensoric and motoric deterioration, claw hand, drop foot, and resorption. The slit skin smear revealed bacterial index (BI) +4 and morphological index (MI) 15%. Histopathological examination revealed granulomas peri-adnexal consists of foamy macrophages, histiocyte epithelioid, with BI +5 on Fite-Faraco stain. This case represented a progression of PNL towards Borderline Lepromatous (BL) leprosy with type I reaction (T1R) and second-degree deformities.
Discussion: Neuritis and emergence of new lesion on reaction episodes often led to confirmation of diagnosis in PNL cases. Another hypothesis regarding silent neuropathy explained a progressive nerve damage without any preceding reactions that may arise on treated and untreated case resulting in extensive deformities.
Conclusion: All leprosy cases probably passed through a neuritic phase before the development of skin lesions, either following reaction episodes or indicates the natural progression of the disease. Any delayed in diagnosis and treatment potentially lead to further deformities and transmission.