Abstract: 【Abstract】 Objective To analyze clinical features and prognosis of Mycoplasma pneumoniae-induced rash and mucositis （MIRM）. Methods Among patients who were diagnosed with erythema multiforme/severe erythema multiforme or Stevens-Johnson syndrome at discharge from the First Affiliated Hospital, Sun Yat-sen University from November 2004 to May 2021, patients with MIRM were screened out according to diagnostic criteria for MIRM and after exclusion of other causes, and their clinical manifestations, laboratory and auxiliary examinations, treatment and prognosis were analyzed. Results Eight patients were found to meet the MIRM diagnostic criteria, including 4 males and 4 females, with the age at onset being 15.63 ± 9.16 years （range, 4 - 30 years）. All the 8 patients had fever, and 5 of them had upper respiratory symptoms such as cough and sore throat. Oral mucosal damage occurred in all the patients, 5 of whom presented with blood crusts on the lips; eye damage occurred in 7 patients, which manifested as conjunctiva hyperemia and increased secretions. All the patients presented with skin lesions, including 5 with targetoid lesions and 4 with blisters. All the patients were serologically positive for anti-Mycoplasma pneumoniae IgM. One patient experienced recurrent upper respiratory tract infections such as dry cough, each episode was closely related to Mycoplasma pneumoniae infection, and whole exome sequencing of the peripheral blood showed heterozygous mutations in the NLRC4 and IRGM genes. Histopathological examination of skin lesions was performed in 3 patients, and the results were consistent with the diagnosis of erythema multiforme. Seven patients were treated with systemic glucocorticoids, 6 with intravenous immunoglobulin, 5 with azithromycin, and 5 with acyclovir, valacyclovir or ribavirin. After an average 2.9-year follow-up, 3 patients were cured, 1 was blind, 1 experienced recurrent dry cough, oral ulcers and rashes on the limbs, and the remaining 3 developed eye damage such as meibomian gland dysfunction, punctal stenosis and corneal epithelial damage. Conclusions MIRM mostly occurred in children and young adults, and was mainly accompanied by prodromal symptoms such as fever, sore throat and cough. MIRM mainly manifested as obvious mucosal damage and some targetoid lesions. Most patients could recover after a single attack, and recurrent episodes may be related to mutations in autoinflammation- and infection-related genes in some patients.

Key words: Erythema multiforme, Stevens-Johnson syndrome, Mycoplasma pneumonia, Mycoplasma pneumonia-induced rash and mucositis, Retrospective studies, Clinical features