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

Area of Science:

• Dermatology
• Infectious Diseases
• Pathology

Background:

• Mycoplasma pneumoniae-induced rash and mucositis (MIRM) is a mucocutaneous condition linked to M. pneumoniae infection.
• It affects children and young adults, often presenting with significant mucosal involvement that can resemble Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN).
• Histopathologic features of MIRM have not been extensively studied.

Purpose of the Study:

• To systematically evaluate the histopathologic changes in Mycoplasma pneumoniae-induced rash and mucositis (MIRM).
• To compare the histopathologic findings of MIRM with other mucocutaneous conditions like SJS/TEN and erythema multiforme.
• To identify distinguishing features of MIRM through histopathologic analysis.

Main Methods:

• Retrospective review of clinical and histopathologic data from eleven confirmed cases of MIRM.
• Detailed recording and analysis of clinical and histopathologic features from available biopsies.
• Comparison of histopathologic findings with clinical presentations and serological confirmation.

Main Results:

• All MIRM cases showed a vacuolar to lichenoid interface reaction with epidermal apoptotic keratinocytes.
• Subepithelial splitting and epithelial necrosis were present in approximately half of the cases, mimicking SJS/TEN.
• A subset of cases exhibited a neutrophil-rich lichenoid infiltrate, associated with leukocytosis and involvement of skin and all three mucosal sites.

Conclusions:

• Histopathologic features of MIRM are often indistinguishable from erythema multiforme or SJS/TEN.
• A neutrophil-rich lichenoid infiltrate may be a distinguishing feature in a small subset of MIRM cases.
• MIRM is considered synonymous with M. pneumoniae-associated erythema multiforme major; clinical and serologic correlation is crucial to differentiate from SJS/TEN.