A diagnostic odyssey: leprosy simulating connective tissue disorder

Leprosy is an infectious disease caused by Mycobacterium leprae, primarily affecting skin and peripheral nerves. Leprosy can manifest in a variety of intricate ways that are similar to connective tissue diseases, with clinical and serological overlaps leading to diagnostic difficulty. We present two cases of leprosy, situated at different poles on the leprosy spectrum, one with Type 2 and one with Type 1 reaction, with positive antinuclear antibodies (ANA), which were initially misidentified as a connective tissue disease. Case 1 describes the rheumatic onset of leprosy with ANA positivity, misidentified as SLE and treated with various immunosuppressants. Case 2 describes the appearance of lesions over the face associated with photosensitivity, with ANA positivity, initially misdiagnosed as SLE, later diagnosed as leprosy through histopathology. These cases underscore the necessity for physicians to look beyond laboratory results alone and use slit skin smears with histopathology as a diagnostic tool, as misdiagnosis can lead to treatment delays and exacerbation of the illness.