A Case Report of Unrecognized Lepromatous Leprosy Occurring in Conjunction with Pemphigus Vulgaris

Leprosy is a chronic, infectious disease of a significant public health concern, primarily affecting the skin and peripheral nerves. The causative agent of this disease is Mycobacterium leprae, and despite its recognition as an ancient affliction, it continues to be occasionally encountered in the southern regions of Thailand. The manifestation and progression of leprosy are known to be influenced by the host's genetic background and immune response.  We present a case of a 45-year-old Thai male who developed new infiltrative papules and nodules while undergoing oral immunosuppressive therapy for the treatment of his underlying pemphigus vulgaris condition. Upon histopathological examination, the presence of histiocytes containing abundant acid-fast bacilli was observed. The patient was successfully treated through a 2-year course of multidrug therapy. This case highlights the challenges in diagnosing leprosy in immunocompromised individuals and underscores the importance of vigilant recognition of the disease by healthcare practitioners. It is imperative that medical professionals remain aware of the potential for leprosy to present in unexpected ways and take necessary steps to diagnose and treat the disease effectively.