Recurrent Heat-Induced Rash in an 8-Year-Old Girl

Case at a Glance

An 8-year-old girl presents with recurrent non-raised erythematous rash on extremities following heat and sun exposure, with resolution typically occurring within 24 hours.

Patient's Story

The patient's mother reports that her daughter consistently develops a flat, non-raised rash on her arms and legs whenever she engages in outdoor activities during warm weather or direct sun exposure. The rash appears shortly after heat exposure and is not associated with itching, pain, or systemic symptoms. The child has a history of seasonal allergies managed with daily cetirizine (Zyrtec). No other medications or known medical conditions are reported.

Initial Assessment

Physical examination during an episode revealed flat, erythematous patches distributed on the arms and legs without urticarial wheals, vesicles, or scaling. The rash was non-tender and non-pruritic. Vital signs were stable, and the patient appeared well. No evidence of systemic involvement or other dermatological conditions was noted.

The Diagnostic Journey

Initial consultation with primary care provider yielded no definitive diagnosis. Given the temporal relationship between heat exposure and rash development, along with the characteristic appearance and distribution, a diagnosis of chronic inducible urticaria (specifically cholinergic or heat urticaria) was considered based on clinical presentation.

Final Diagnosis

Chronic inducible urticaria (heat-induced urticaria) - a subtype of physical urticaria triggered by elevated body temperature and heat exposure.

Treatment Plan

Continue current antihistamine therapy with cetirizine. Implement preventive measures including gradual heat exposure, staying hydrated, wearing lightweight clothing, and seeking shade during peak sun hours. Consider additional H1 antihistamines if symptoms persist or worsen.

Outcome and Follow-up

The patient continues to experience episodic rashes with heat exposure, but symptoms typically resolve within 24 hours without intervention. Family educated on trigger avoidance and when to seek further medical attention. Follow-up planned if symptoms worsen or fail to respond to current management.