Mycoplasma pneumoniae-Induced Rash and Mucositis: Clinicopathologic Characterization of 11 Cases.

BACKGROUND

Mycoplasma pneumoniae -induced rash and mucositis (MIRM) is a mucocutaneous eruption affecting children and young adults with respiratory tract or clinically occult infection by M. pneumoniae . Mucosal involvement is often robust and may raise concern for Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN). Histopathologic changes in MIRM have not been systematically evaluated.

METHODS

Eleven cases of clinically and serologically confirmed MIRM with biopsies available were included in this study. Clinical and histopathologic features were reviewed and recorded.

RESULTS

All cases displayed a vacuolar to lichenoid interface reaction with apoptotic keratinocytes or cytoid bodies confined to the epidermis. Subepithelial split and epithelial necrosis were observed in about half of the cases, some of which closely mimicked SJS/TEN histopathologically. There was a predominance of neutrophils over lymphocytes in the lichenoid infiltrate in a small subset of cases, a finding that was associated with leukocytosis and concomitant disease involvement of skin and all three mucosal sites.

CONCLUSIONS

The majority of MIRM cases demonstrated histopathologic features indistinguishable from those of erythema multiforme or SJS/TEN, with the exception of a neutrophil-rich lichenoid infiltrate observed in a small subset of cases. MIRM is essentially synonymous with erythema multiforme major associated with M. pneumoniae infection. Correlation with clinical and serologic findings is necessary to exclude SJS/TEN.