Unexplained Recurrent Rash in a Child: an Atypical Presentation of Mycoplasma pneumoniae Infection

Abstract

Introduction Mycoplasma pneumoniae is a common respiratory pathogen and a frequent cause of community-acquired pneumonia. Rarely, this bacterium can cause extrapulmonary manifestations, including mucocutaneous involvement. [1] We report a clinical case of M. pneumoniae infection causing recurrent rashes resembling lupus erythematosus and erythema infectiosum, highlighting the need to consider this pathogen in unexplained cutaneous eruptions. Case Presentation An 8-year-old girl developed eye irritation followed by a red, symmetrical rash spreading from her face to the limbs over several days. Recurrent erythematous plaques appeared weekly, each episode lasting three days. Antihistamine therapy was ineffective. No systemic symptoms or fever were observed, the mucous membranes remained unaffected. Cutaneous lupus erythematosus and parvovirus B19 infection were considered in the differential diagnosis, but subsequent laboratory investigations were negative. A complete blood count showed no significant abnormalities, however, extended laboratory testing revealed positive M. pneumoniae IgM antibodies. Antibacterial therapy with clarithromycin was initiated. Longterm follow-up was unavailable, as the patient did not return due to clinical improvement. Discussion About 25% of M. pneumoniae infections manifest with cutaneous eruptions. [2] The factors determining the presentation and severity of M. pneumoniae-related cutaneous disease remain unclear. The condition is considered immune-mediated, with immune complex formation causing tissue injury. [3] These clinical cases are highly variable, ranging from nonspecific rash to toxic epidermal necrolysis. Despite the different manifestations, they may occur during active or asymptomatic infection. [4] The most common cutaneous presentation is a non-specific exanthem [2], which begins as a single macule and may spread to the face and limbs, usually resolving within 2-22 days. [4]. M. pneumoniae infection is usually treated with macrolides and cutaneous lesions can be managed symptomatically with topical emollients. [5] Conclusions An awareness of the presentations of M. pneumoniae as a cutaneous disease is essential, as they may occur at any stage of the disease and be mistaken for other conditions. A high index of suspicion is important for timely diagnosis and appropriate treatment.