Case Study: Acute Intermittent Urticaria in a 2-Year-Old Male

Case at a Glance

A healthy 2-year-old male with no known allergies experienced multiple, sudden-onset episodes of migratory urticaria over a 24-hour period. The wheals appeared in various locations and resolved spontaneously within 30-60 minutes without any clear trigger or associated systemic symptoms.

Patient's Story

The patient is a 2-year-old male with a history of only keratosis pilaris on his arms. He takes no medications and has no known allergies. Two days prior to presentation, he had swam in a chlorinated family pool without being rinsed off afterward. On the morning of presentation, his mother noted a small cluster of hives on his knee, which rapidly progressed to involve his entire left flank and stomach. The mother prepared to take him to an urgent care clinic, but the extensive urticaria completely resolved on its own within an hour. Later that day, after a 30-minute period of playing outside, the patient developed new hives on his feet, knees, and stomach, which again resolved spontaneously after about 30 minutes. However, a subsequent, longer period of outdoor play (1.5 hours) did not provoke any skin reaction. That evening, after the child rubbed his face, localized hives appeared in that area and faded within 20 minutes. The mother noted no new foods, detergents, or environmental exposures. She observed no oral lesions or signs of fever or illness, though she noted what appeared to be an erupting molar.

Initial Assessment

The patient was assessed at home by his parent. The initial presentation was described as widespread, raised wheals consistent with urticaria on the trunk. Key findings were the transient and migratory nature of the lesions. Crucially, there were no signs of systemic involvement or anaphylaxis, such as respiratory distress, stridor, facial or lingual edema, or lethargy. The patient's general health appeared unaffected during and between episodes.

The Diagnostic Journey

The primary diagnostic challenge was identifying a trigger for the acute urticaria. The parent systematically considered potential causes, including environmental allergens (grass), contactants (new detergents), and food allergens, but the history did not support these. The recent exposure to a chlorinated pool was considered as a potential skin sensitizer, though the delayed onset and transient nature made this less likely. The development of hives after physical pressure (rubbing his face) raised the possibility of dermatographism, a type of physical urticaria. Following an online consultation for information, the most likely differential diagnosis was identified as post-viral urticaria, which is a very common cause of acute hives in young children and can occur without other prominent symptoms of a viral illness. Lacking a definitive trigger, idiopathic urticaria was also a primary consideration.

Final Diagnosis

Acute Urticaria, likely idiopathic or post-viral in nature. The transient, migratory pattern without a clear, consistent trigger is characteristic of this condition in the pediatric population. A component of dermatographism may also be present.

Treatment Plan

Given the self-resolving nature of the episodes and the absence of significant distress or systemic symptoms, a 'watch-and-wait' approach was adopted. The parent was counseled to monitor the child closely for any signs of airway compromise (difficulty breathing, wheezing, swelling of the lips or tongue), which would necessitate immediate emergency medical care. Over-the-counter, non-sedating antihistamines were considered as a potential option for symptomatic relief if the episodes became more frequent, prolonged, or pruritic.

Outcome and Follow-up

The episodes remained brief and self-limiting. The follow-up plan involved continued observation at home. The parent was advised that if the urticarial episodes persisted for more than six weeks, the condition would be classified as chronic urticaria, and a formal evaluation by a pediatrician or allergist would be warranted to consider further diagnostic workup. The parent found educational resources on acute urticaria helpful for understanding the condition's typically benign and self-limited course.