Next-generation sequencing-assisted diagnosis of a case of leprosy misdiagnosed as erythema multiforme

Leprosy is a chronic infectious disease caused by Mycobacterium leprae or Mycobacterium lepromatosis that is mainly transmitted through droplets from the nose and mouth of untreated patients. Owing to the lack of specific serological markers and clinical manifestations, leprosy can be easily confused with other skin lesion-related diseases and is difficult to distinguish.This study introduces and summarises the diagnosis and treatment process of a case of leprosy misdiagnosed as erythema multiforme for a long time. A 43-year-old female was admitted to our hospital because of "repeated fever with superficial lymphadenopathy and systemic rash in May". The diagnosis of the patient was based on the two main clinical characteristics of superficial lymphadenopathy and systemic pleomorphic erythema by using a combination of multiple samples of lymph nodes and skin, routine pathological examination, immunohistochemistry, acid-fast, silver hexamine, periodic acid-Schiff (PAS) staining, and second-generation gene sequencing of fresh biopsy tissue. The patient was treated with dapsone, rifampicin, and clofazimine at the Institute of Dermatology and Venereal Diseases. After treatment for 1 year, her temperature returned to normal, the area of facial erythema decreased, and the volume of axillary lymph nodes had gradually reduced.In conclusion, special pathological staining and second-generation gene sequencing show promising advantages in distinguishing leprosy from other skin lesion-related diseases.