504 Mycoplasma Pneumoniae-Associated Stevens-Johnson Syndrome; Clinical and Histological Features

Mycoplasma pneumoniae (M. pneumoniae) induces various types of skin manifestations and potentially develop extensive mucous/eye lesion consistent with Stevens-Johnson syndrome(SJS). Specifically, in children cases with SJS, M.pneumoniae infection, as well as various drugs, is considered a major cause of SJS. M.pneumoniae-associated SJS cases often show only mucous/eye lesions without skin lesions, whereas typical drug-induced SJS cases show both skin lesions and mucosal lesions. In addition, palatal small vesicles are thought to be characteristic in M.pneumoniae-associated SJS. We aimed to investigate the clinical and histological findings of M.pneumoniae-associated SJS. Furthermore we performed M.pneumoniae staining in mucous lesions to detect M. pneumoniae-infected cells. The cases in our study (n=2) showed mucosal lesions and high fevers, which were suspected to be M.pneumonae-associated SJS. The patients had ocular lesions and severe mucous erosions including palatal small vesicles, however there were no skin lesions. Tests of serology and direct pathogen detection indicated M.pneumonae infection. Lip biopsies revealed sparse mucoepithelial necrotic cells in only basal cells and band-like inflammatory cell infiltrate in upper lamina propria mucosae. On the other hand, drug-induced SJS is widespread-epithelial cell necrosis through mucoepithelium. In M.pneumonae staining, there were positive cells in lamina propria mucosae, whereas there were no positive cells in mucoepithelium. From our study, M.pnumoniae-associated SJS is clearly distinguishable from drug-associated SJS in clinical manifestation and pathological findings. In addition, M.pneumonae infected cells in lamina propria mucosae might influence to basal layer cell death in M.pnumoniae-associated SJS.