Itchy Rash in an 11-Year-Old

An 11-year-old male presented to clinic with a 1- day history of a pruritic rash. The child and mother describe the rash as large welts all over his body. His mother first noticed the rash the night before the office visit. 

The rash initially started on his waist, but by the next day had spread to his stomach, legs, chest and back. The rash was described as very itchy and the patient had been scratching at it since it first appeared. His mother tried using Cetaphil lotion without any improvement. 

The patient and mother denied any pain, bleeding, draining or crusting associated with the rash. On further questioning, his mother denied changing anything out of the patient’s normal routine (i.e., soaps, lotions, detergents) and he denied consuming any new foods. They also denied any exposure to others with a similar rash. On review of symptoms, the patient and mother deny any fevers, weight loss, difficulty breathing, nausea, vomiting, diarrhea or facial edema. Of note, the patient did have upper respiratory symptoms, including congestion and cough that resolved a few days before this visit. 

On physical examination, his vitals were: temperature = 98.6 °F; respiration rate = 22 breaths/min; weight = 30.4 kg (67 lb 0.3 oz). The patient appeared in good condition, well nourished and in no acute distress. His HEENT exam reveals an erythematous oral pharynx with enlarged erythematous tonsils without exudate, palatal petechial rash, macroglossia or swollen lips. He also had a small amount of periorbital edema without pain or erythema (Figure 1). The remainder of his HEENT was unremarkable.

His neck was supple, without adenopathy. His lung, cardiac and abdominal exams were all normal. His skin exam revealed multiple raised, round erythematous lesions on his face, trunk and extremities, sparing only his palms and soles. The largest lesions were located on his left calf (approximately 16 cm × 8 cm) and right forearm (approximately 8 cm × 8 cm) (Figure 2). Smaller, raised erythematous wheals surrounded both lesions.

In addition to these larger lesions, the patient also had multiple small, at times confluent, erythematous raised lesions on his right upper chest and right lower quadrant, with some demonstrating central clearing with a skin color tone. His waistline was also erythematous, but the lesions were not raised like the others. The patient also had erythema to both cheeks (Figure 1). All the erythematous lesions had a discrete border and blanch with gentle pressure. 

What caused this rash?

(Answer and discussion on next page)

Answer: Acute urticaria

Due to the presence of an erythematous, raised, pruritic rash, with lack of systemic symptoms (nausea, vomiting, respiratory distress, or mucous membrane edema) the patient was ultimately diagnosed with acute urticaria. He was treated with an oral antihistamine and his mother was instructed on the application of a topical steroid to the lesion sites.

On a follow-up phone call, 48 hours after initiation of treatment, the patient had experienced a reduction in the severity of his pruritus and number of wheals.

Acute urticaria is a common, self-limited immunologic reaction that 15% to 25% of the general population experience at some point in their lifetime.¹ This cutaneous rash consists of transient, pruritic, erythematous wheals with central pallor and well-defined borders. The wheals can be circumscribed and discretely distributed or coalescent. Urticaria can be found nearly anywhere on the body, although it is most frequently found on the trunk and extremities.² 

Urticaria is a common presentation seen in the pediatric emergency department, especially for children experiencing first-time acute episodes. The diagnosis is generally made following a detailed history and physical exam, although the specific etiology is usually not elucidated at that time. Thus, having an adequate understanding of the etiologies of urticaria can allow pediatricians to perform relevant clinical assessments, prevent unnecessary workup, and counsel parents regarding specific allergens with which contact should be avoided.^1,2  

Urticarial rashes most often develop as a hypersensitivity response to an external stimulus that activates mast cell granulation through an IgE-mediated process. Inciting agents bind to IgE on sensitized mast cells, causing a cross-linking phenomenon and subsequent degranulation. Through degranulation, the mast cell releases preformed inflammatory mediators into the interstitium, the most important of these being histamine, which regulates vasodilatation and fluid secretion.³ A number of other pathways have also been suggested for certain etiologies of urticaria, such as the complement system and plasma effector systems for viral and bacterial etiologies, in addition to abnormalities in arachidonic acid metabolism when the etiology is secondary to nonsteroidal anti-inflammatory drugs or aspirin.¹

As seen in this case, the majority of urticarial rashes will be acute, lasting less than 2 weeks. Chronic urticaria is defined as lasting longer than 6 weeks.^4,5 Acute urticaria has myriad  causes, especially in the pediatric population (Table 1). However, one of the most frequent culprits of the exanthema, and the root of more than 80% of pediatric cases, is viral infection.^2,4 Similar to our patient, the rash develops toward the end of the viral illness as the body clears the infection. 

Upper respiratory tract infections and acute gastroenteritis are major causes of a first attack of acute urticaria, which suggests these should be considered when determining diagnosis and etiology.^1,2,4 However, a lower prevalence of infectious etiologies and increasing food and medication causes as age increases suggests food and medication triggers should be considered in older children and adults.¹ Other causes of acute urticaria include toxins from insect bites and stings, food allergens, and physical contact with substances that a child has been sensitized to, such as specific plants or textiles.⁶

Subtypes of urticaria include contact, aquagenic, cholinergic, cold, delayed pressure, localized, heat, solar and vibratory. The differential diagnosis of this presentation can range from self-limited hypersensitivity reactions to multisystem inflammatory diseases. Common mimickers of acute urticaria include urticaria multiforme, serum sickness-like reactions, Henoch-Schonlien purpura, acute hemorrhagic edema of infancy, systemic onset juvenile idiopathic arthritis, cryopyrin-associated periodic syndromes, and urticarial vasculitis (Table 2).^6,7 The morphology and histology of the rash, inflammatory biomarkers, and the extracutaneous manifestations associated with the presentation can help to distinguish self-limited conditions from multisystem diseases.^5,6  

There are multiple subtypes of urticaria, and each of the potential etiologies of urticaria requires a different management strategy. Untreated urticaria can be associated with high direct and indirect health care costs, as well as impaired quality of life secondary to decreased physical function, emotional problems, and limitations of social interactions. Because most urticarial symptoms are mediated by the action of histamine on H1-receptors located on endothelial cells and sensory nerves, the current first-line treatment for most subtypes of urticaria is second-generation H1-antihistamines.⁸ These medications are also associated with rapid onset, prolonged duration that allows for once-daily dosing, and a benign safety profile even at higher doses.⁸ However, previous studies in tertiary care clinics have shown that only 40% of patients experience complete remission of their symptoms and some patients only experience a reduction in the severity of their pruritus and number of wheals.² 

Medication failure should not be determined on the basis of continued symptoms after use of 1 particular antihistamine, as efficacy is often patient specific. Thus, trials of more than 1 antihistamine should be utilized in addition to daily dosing rather than on an as-needed basis to increase the chance of resolution. Pediatric patients that are ultimately not responsive to H1- and H2-antihistamines—or have severe symptoms involving angioedema or severe, impactful pruritus—should be given a short burst of oral glucocorticoids (0.5 to 2 mg/kg/day) followed by a 5- to 7-day taper.^2,7  The risks of using prolonged glucocorticoids outweigh the risk of symptom recurrence following glucocorticoid discontinuation. Leukotriene modifiers can also be used as either monotherapy or an adjunct before considering corticosteroids. 

Close follow-up is suggested to monitor for resolution of the rash and any associated symptoms.^2,5 Patients and parents should be counseled on the generally benign, self-limiting course of the disease and the fact that a cause is often not elucidated, about the lack of a cure, and that recurrence is not uncommon. In fact, approximately 20% to 30% of patients who present with acute urticaria progress to chronic or recurrent urticaria.²

Chris Schreier, ARNP, is a pediatric nurse practitioner in the Department of Pediatrics, UF Health in Gainesville, Florida.  

Shayla Salgado is a medical student at the College of Medicine, University of Florida in Gainesville, Florida. 

Ryan St. Pierre-Hetz is a medical student at the College of Medicine, University of Florida in Gainesville, Florida. 

Maria Kelly, MD, is a clinical associate professor in the Department of Pediatics at the University of Florida in Gainesville, Florida. 

References

1. Tsakok T, Du toit G, Flohr C. Pediatric urticaria. Immunol Allergy Clin North Am. 2014;34(1):117-139.
2. Poonawalla T, Kelly B. Urticaria: a review. Am J Clin Dermatol. 2009;10(1):9-21. 
3. Atkinson NF Jr, Yunginger JW, Busse WW, et al, eds. Middleton’s Allergy: Principles and Practice. 6th ed. Philadelphia, PA: Mosby; 2009:1063-1081.
4. Deacock SJ. An approach to the patient with urticaria. Clin Exp Immunol. 2008;153(2):151-161.
5. Peroni A, Colato C, Schena D, Girolomoni G. Urticarial lesions: if not urticaria, what else? The differential diagnosis of urticaria: part I. Cutaneous diseases. J Am Acad Dermatol. 2010;62(4):541-555.
6. Langley EW, Gigante J. Anaphylaxis, urticaria, and angioedema. Pediatr Rev. 2013;34(6):247-257. 
7. Mathur AN, Mathes EF. Urticaria mimickers in children. Dermatol Ther. 2013;26(6):467-475. 
8. Ortonne JP. Urticaria and its subtypes: the role of second-generation antihistamines. Eur J Intern Med. 2012;23(1):26-30.