Pediatric Mycoplasma pneumoniae-induced rash and mucositis in China: clinical spectrum, co-infections and risk factors for recurrence-a retrospective cohort study.

Background: Mycoplasma pneumoniae-induced rash and mucositis (MIRM) is a unique entity distinct from both erythema multiforme and Stevens-Johnson syndrome/toxic epidermal necrolysis. There are limited data on pediatric cases of MIRM in China. Objective: To evaluate the clinical characteristics and recurrence frequency of pediatric cases of MIRM and to summarize the co-infections beyond M. pneumoniae infection. Methods: This retrospective study was conducted through a chart review of patients with MIRM admitted to dermatology inpatient department from September 2017 to July 2021. Pediatric patients with MIRM 4 years to 12 years who met Canavan's criteria were included in the study. Results: A total of 23 patients with MIRM aged 7.86 ± 2.92 years were included. Oral mucosa was the most common site of mucosal involvement. Average number of involved mucous membranes was 2.83 ± 0.89. Average length of hospital stay was 10.30 ± 3.34 days. Length of hospital stay in recurrent cases was shorter than isolated cases (6.3 days vs. 10.17 days). Recurrence was observed in 21.7% of patients. The number of mucosal membranes involved was more in the first episode of recurrent cases than isolated cases (3.2 vs. 2.72). Of all patients, 47.8% were co-infected with pathogens apart from M. pneumoniae. Recurrence rate of the co-infection group was 36.4%. Conclusion: We report observations from the largest pediatric cohort with MIRM in China. Patients with younger age at onset had more severe skin and mucosal involvement, even similar to SJS/TEN. A higher recurrence rate and incidence of co-infections were observed in our cohort. The co-infection group had a higher recurrence rate, which further supports the concept of reactive infectious mucocutaneous eruption.