Less frequently observable infectious agents associated with EM are Mycoplasma pneumoniae, Histoplasma capsulatum, and parapoxvirus (orf). Rarely, EM is triggered by drug eruption or systemic disease. Individuals of all age groups and races can be affected by EM. However, it is predominantly observed in young adult patients (20-40 years of age), and there is a male predominance.
Patients typically present with the abrupt onset of symmetrical red papules that evolve into typical and atypical targetoid lesions. Lesions evolve in 48-72 hours, favoring acrofacial sites that then spread down towards the trunk. Systemic symptoms such as fever and arthralgia may accompany the skin lesions.1-3
Erythema multiforme is recognized in two forms: EM minor and EM major. Both forms share the same characteristic of target lesions. However, the presence of mucosal involvement distinguishes the two. Mucosal involvement is absent or mild in EM minor, while mucosal involvement in EM major is often severe.2,3 Painful bullous lesions are commonly present in the mouth, genital, and ocular mucous membranes. Severe symptoms can often result in difficulty eating and drinking.
Diagnosis is largely clinical. Further histologic study may accompany diagnoses to exclude differential diagnosis. In EM, direct immunofluorescence (DIF) is negative. Histopathology reveals apoptosis of individual keratinocytes.1,2
Therapeutic treatment for painful bullous lesions in the mouth involve antiseptic rinses and anesthetic solutions. Preventive treatment for patients with HSV-associated EM recurrence includes oral acyclovir or valacyclovir.2
In this patient, a punch biopsy was performed, confirming the diagnosis. A DIF was negative, and a chest x-ray was negative. Treatment was initiated with oral acyclovir, doxycycline, and a prednisone taper. In addition, topical clobetasol propionate and magic mouthwash (Maalox/lidocaine/nystatin) was prescribed. The patient was placed on daily suppressive valacyclovir to prevent frequent recurrence of EM.
Dr. Donna Bilu Martin
This case and photo were submitted by Ms. Pham, the University of California, Los Angeles, and Dr. Sateesh, San Diego Family Dermatology. Dr. Bilu-Martin edited the column.
Dr. Bilu Martin is a board-certified dermatologist in private practice at Premier Dermatology, MD, in Aventura, Fla. More diagnostic cases are available at mdedge.com/dermatology. To submit a case for possible publication, send an email to dermnews@mdedge.com.
References
1. Hafsi W and Badri T. Erythema Multiforme, in “StatPearls [Internet].” Treasure Island, Fla.: StatPearls Publishing, 2022 Jan.
2. Bolognia J et al. Dermatology. St. Louis: Mosby/Elsevier, 2008.
3. Oakley A. Erythema Multiforme. DermNet NZ. 2015 Oct.