urticaria multiforme

A Boy With a Rapidly Progressing Rash

Sanjay Mehta, MD
Gerald C. Almazan, MD
Srividya Naganathan, MD
Volume 15 - Issue 2 - February 2016

A 2-year-old boy with no significant medical history presented to the emergency room with a pruritic rash that began 3 days earlier. About 2 weeks before the onset of the rash, the boy’s parents reported that he developed nasal congestion, cough, and fever. He was seen at a local emergency room and diagnosed with acute otitis media and started on amoxicillin-clavilunic acid suspension. 

On the eighth day of his antibiotic course, the patient developed a pruritic rash on his trunk (Figure 1). He came into our emergency room and he was diagnosed with an allergic reaction to amoxicillin. The antibiotic was discontinued and the patient began taking diphenhydramine (Benadryl) as needed for hives and itching. Over the next 2 days, his rash and pruritus worsened. It spread toward his extremities and he developed swelling of his hands and feet. The patient was up-to-date with all immunizations.

Physical examination revealed a boy who was nontoxic and in no acute distress. His dermatologic exam revealed generalized blanching, annular papules and polycyclic plaques, with dusky centers on the face, trunk, extremities (Figure 2), hands (Figure 3), and feet. Hand and foot angioedema was also noted. There was no mucous membrane involvement. 

Results of a serum complete blood count with differential, comprehensive metabolic panel, C-reactive protein, rapid strep test, and urinalysis were normal.

A dermatologic exam revealed generalized blanching, annular papules and polycyclic plaques, with dusky centers on the face, trunk, extremities (Figure 2), hands (Figure 3), and feet 

What is the etiology of this rash?

(Answer and discussion on next page)

Answer: Urticaria multiforme 

The patient received a diagnosis of urticaria multiforme (UM), which is an acute and benign cutaneous hypersensitivity reaction that affects infants and small children—usually found in children 4 months to 4 years of age.1,2 UM is a morphologic subtype of urticaria that demonstrates rapid progression. 

A dermatologic exam revealed generalized blanching, annular papules and polycyclic plaques, with dusky centers on the face, trunk, extremities (Figure 2), hands (Figure 3), and feet

Initially, UM can appear as macules, papules, or plaques that rapidly progress to form characteristic blanching, annular, and polycyclic wheals with dusky, ecchymotic centers. The lesions are commonly located on the trunk, extremities, and face, associated with facial and/or acral angioedema. This angioedema is self-limited and it is not associated with laryngoedema.3 Other commonly associated clinical features are fever, pruritus, and dermatographism.

Differential diagnoses to consider are erythema multiforme, serum sickness-like reaction, and urticaria vasculitis. Diagnosis can be made based on clinical history and physical examination, and extensive diagnostic testing is unnecessary. Many children with UM have a history of a recent viral or bacterial illness or recent antibiotic use.  

For most cases, treatment is supportive with antihistamines and discontinuation of the offending agent. Most cases last from 2 to 12 days. 

Patient’s course

The patient was given diphenhydramine and a dose of prednisone in the emergency room, and he was admitted to the pediatric unit for further observation. Diphenhydramine was switched to hydroxyzine, which provided better relief of his pruritus. The patient’s rash lasted 12 days from initial onset, and he is now back to his normal, usual state of health.

Gerald C. Almazan, MD, is a Pediatric Hospitalist at CentraState Medical Center in Freehold, New Jersey.

Sanjay Mehta, DO, FAAP, is the Division Chief of the Pediatric Emergency Department and Medical Director of Inpatient Pediatric Associates at CentraState Medical Center in Freehold, New Jersey.

Srividya Naganathan, MD, FAAP, is a Clinical Associate Professor of Pediatrics at Rutgers Robert Wood Johnson Medical School in New Brunswick, New Jersey, and a Pediatric Hospitalist at K. Hovnanian Children’s Hospital in Neptune City, New Jersey.

Kirk Barber, MD, FRCPC—Series Editor, is a clinical professor of Medicine and Commuinity Health Sciences at the University of Calgary in Calgary, Alberta, Canada. 

References

  1. Shah KN, Honig PJ, Yan AC. Urticaria multiforme: a case series and review of acute annular ursdticarial hypersensitivity syndromes in children. Pediatrics. 2007;119(5):e1117–e1183.
  2. Tamayo-Sanchez L, Ruiz-Maldonado R, Laterza A. Acute annular urticaria in infants and children. Pediatr Dermatol. 1997;14(3):231–234.
  3. Emer JJ, Bernardo SG, Kovalerchik O, Ahmad M. Urticaria multiforme. J Clin Aesthet Dermatol. 2013;6(3):34–39.