A boy bullied by bullae

The case

The mother of a 9-year-old boy brings him to the office for urgent evaluation of undiagnosed widespread blistering of the skin and mouth. The eruption has occurred 2 to 3 times a year for the last 3 years, and the oral lesions have been severe enough on several occasions to prompt hospitalization for dehydration. She wants an answer to the mystery now. What are you going to tell her?

Diagnosis: Recurrent erythema multiforme syndrome

Clinical features and etiology

Erythema multiforme (EM) affects persons aged younger than 20 years in 50% of cases.¹ It is characterized by expanding erythematous papules with dusky centers that often evolve and develop central bullae over 10 or more days. Rupture of the bullae and subsequent crust formation and pale surrounding rings give rise to the diagnostic target lesions.² Although there is a predilection for the distal extremities, particularly the palms and soles, the eruption may become generalized. The mucous membranes, particularly the mouth, may also become involved, with erosions, ulcerations, or bullae on the lips, oropharynx, conjunctiva, anus, or vulva. Lesions may be pruritic or sometimes painful, especially around the mouth.^1,3

Recurrent EM is defined as the presence of the classic target lesions in a symmetric pattern that occur 3 or more times. In most cases, patients with recurrent EM will have oral involvement. One study of recurrent EM found episodes recurred for an average of 6 years.⁴

Erythema multiforme can be caused by many factors, including infection with herpes simplex virus (HSV) or mycoplasma pneumoniae; drugs such as phenytoin, penicillin, and sulfonamides; or as an idiopathic reaction.¹ Herpes simplex virus is the most frequently identified cause of EM; it has been found in 61% to 100% of cases.^2,4

Pathology

Dermatopathology of erythema multiforme shows edema of the upper dermis with a mononuclear perivascular infiltrate. In addition, subepidermal bullae may be seen, as well as keratinocyte apoptosis and focal epidermal necrosis.^1,3

Diagnosis and differential diagnosis

Symmetric, bilateral, target lesions, particularly of the distal extremities, are virtually diagnostic. The clinician can usually exclude other acute eruptions such as urticaria, morbilliform drug eruptions, viral exanthems, and other reactive erythemas by the absence of target lesions. When mucus membranes are involved, one may also think of a primary herpetic gingivostomatitis, Steven-Johnson syndrome, autoimmune bullous diseases, fixed drug eruption, and systemic lupus erythematosus.^1,3

Treatment

All potential triggers, such as medications, should be discontinued and infections treated when possible. Management of EM is primarily supportive with oral antihistamines, pain management, fluid resuscitation as needed, and local wound care. When oral mucous membrane involvement is severe, oral corticosteroids may be considered. Recurrent HSV can be treated with prophylactic oral antiviral agents.^2,3

Our patient

Our patient experienced a rapid recovery while taking hydroxyzine and a 10-day tapering course of prednisone. Since his EM was associated with recurrent herpes labialis, he was placed on prophylactic oral valacyclovir with continued monitoring.

References

• Wolff K, Johnson RA. Erythema multiforme syndrome. Fitzpatrick's Color Atlas and Synopsis of Clinical Dermatology. 6th ed. New York: McGraw-Hill Professional; 2009:148-151.

• Kamala KA, Ashok L, Annigeri RG. Herpes associated erythema multiforme. Contemp Clin Dent. 2011;2(4):372-375.

• Sokumbi O, Wetter DA. Clinical features, diagnosis, and treatment of erythema multiforme: a review for the practicing dermatologist. Int J Dermatol. 2012;51(8):889-902.

• Wetter DA, Davis MD. Recurrent erythema multiforme: clinical characteristics, etiologic associations, and treatment in a series of 48 patients at Mayo Clinic, 2000 to 2007. J Am Acad Dermatol. 2010;62(1):45-53.