[Erythema multiforme majus and Chlamydia pneumoniae infection]

Erythema multiforme majus of infectious origin is an acute eruptive syndrome seen more commonly in young subjects and characterised by an appearance of round target lesions. In most cases, it is associated with infection involving Herpes simplex virus or Mycoplasma pneumoniae. We report an original case of erythema multiforme majus subsequent to infection with Chlamydia pneumoniae.

An 18 year-old man was hospitalised for management of generalised skin rash comprising lesions in rings, associated with bullous and post-bullous lesions, chiefly in the oral (preventing eating) and genital areas in a setting of febrile cough. Various bacterial agents (Mycoplasma pneumoniae, Chlamydia pneumoniae) and viral agents were suspected, but serological testing for Chlamydia pneumoniae alone was positive with IgM of 128 IU and IgG of 64 IU. The outcome was favourable within several days following administration of symptomatic treatment (rehydration, mouthwashes, etc.) and aetiological treatment (acyclovir: 30 mg/kg/d, ofloxacine: 400 mg/d). At D15, serologic tests for Mycoplasma pneumoniae continued to be negative. Anti-Chlamydia pneumoniae IgM and IgG were 256 IU. At D30, IgM was 128 IU while IgG remained at 256 IU.

The existence of a systematic skin rash comprising typical target lesions and mucosal lesions in the oral and genital areas suggested to us a diagnosis of erythema multiforme majus. Screening for the agents generally responsible was negative and drug-induced rash was ruled out. Serological tests for Chlamydia pneumoniae were positive at various times, resulting in diagnosis of erythema multiforme majus secondary to infection with Chlamydia pneumoniae. Following demonstration of the presence of Chlamydia pneumoniae using reliable methods and the elimination of other causes of erythema multiforme majus, dermatologists should opt for this aetiology in order to optimise treatment.