Progression of pure neural leprosy towards borderline lepromatous leprosy

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 progress to visible skin lesion. 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, earlobe infiltrate, punched-out lesion on the face, hypopigmentation on the trunk and extremities with sensory impairment, nerve enlargement alongside sensory and motor deterioration, claw hand, drop foot and resorption of phalanges. The slit skin smear revealed bacterial index (BI) +4 and morphological index (MI) 15. Histopathological examination revealed periadenexal granulomas consisting of foamy macrophages, histiocytes, epithelioid cells, with BI +5 on Fite-Faraco stain. This case represents progression of PNL towards Borderline Lepromatous (BL) leprosy with type I reaction (T1R) and second-degree deformities. Neuritis and emergence of new lesion on reaction episodes often lead 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 cases resulting in extensive deformities. All leprosy cases probably pass through a neuritic phase before the development of skin lesions either following reaction episodes or indicate the natural progression of the disease. Any delay in diagnosis and treatment potentially lead to further deformities and transmission.