Multibacillary Lepromatous Leprosy in an Endemic Area: A Two-Year Diagnostic Delay and the Role of Slit-Skin Smear and PCR

Multibacillary lepromatous leprosy can mimic other dermatological conditions, delaying diagnosis. In areas with limited access to histopathology, the slit-skin smear (SSS) is an accessible tool that, together with clinical findings, can support the diagnosis and the start of treatment, while PCR of SSS material may provide complementary confirmation.

A 63-year-old male from Montería (Córdoba, Colombia), with a history of chronic venous insufficiency, presented with a two-year history of characteristic skin lesions, including nodular infiltration of the earlobe, a hyperkeratotic plaque with hypoesthesia on the right elbow, and diffuse cutaneous involvement of the chest and abdomen. SSS of the earlobe showed acid-fast bacilli with a bacterial index of 4+ (Ridley scale). Based on the clinical findings and the smear result, multibacillary lepromatous leprosy was diagnosed, and multidrug therapy was started per the WHO regimen without histological confirmation. Real-time PCR performed approximately two and a half months later was positive for Mycobacterium leprae, and a skin biopsy performed about 18 months after diagnosis showed foamy histiocytes consistent with the lepromatous pole. After completing 12 months of treatment, the patient showed favorable clinical progress.

In endemic areas with limited access to histopathology, clinical suspicion of characteristic leprosy lesions, supported by SSS, can allow the diagnosis and the start of multidrug therapy without depending on histological confirmation. As a single case, it does not demonstrate that this approach shortens time to treatment or prevents disability.