Mycoplasma pneumoniae (M. pneumoniae) induces various types of skin manifestations　and potentially develop extensive mucous/eyes lesion consistent with Stevens-Johnson syndrome(SJS). Specifically, in children cases with SJS, M.pneumoniae infection is considered a major cause of SJS as well as drugs. M.pneumoniae-associated SJS cases often show only mucous/eyes lesions without skin lesions, whereas typical drug-induced SJS cases show both skin lesions and mucosal lesions. In addition, palatal small vesicles are thought as 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 lesion to detect M. pneumoniae-infected cells.
The cases in our study (n=2) showed mucosal lesions and high fever, 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. Test of serology and direct pathogen detection indicated M.pneumonae infection. 
Lip biopsies revealed sparse mucoepithelial necrotic cells at only basal cell and band-like inflammatory cell infiltrate at 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 cell in mucoepithelium.
From our study, M.pnumoniae-associated SJS was clearly distinguished from drug-associated SJS in clinical manifestation and pathological findings. In addition, M.pneumonae infected cells in in lamina propria mucosae might influence to basal layer cell death in M.pnumoniae-associated SJS.

Mycoplasma pneumoniae-associated Stevens-Johnson syndrome; clinical and histological features