D1.304 - Exercise-induced anaphylaxis misdiagnosed as cholinergic urticaria in a child: a case report

Recurrent and chronic urticaria in children remains a challenging problem in modern allergology. Its diagnosis and management often require significant medical resources and specialized expertise to avoid inappropriate treatment. Accurate diagnosis is crucial, as it may be life-saving. We present a diagnostically challenging case of an 8-year-old boy with recurrent wheals occurring after physical exertion and sweating for three months prior to admission to our center. The patient was initially partially examined by a general practitioner and diagnosed with cholinergic urticaria based on trigger-related history. However, according to current concepts of chronic urticaria, different pathogenic mechanisms may coexist in the same patient, and diagnostic evaluation should follow a comprehensive protocol.

The patient underwent laboratory investigations including complete blood count, biochemical tests, and specific in vitro allergological testing, as well as instrumental diagnostic procedures. Provocation tests for inducible urticaria (heat, cold, dermographism, vibration, and physical exertion) were performed. An autologous serum skin test (ASST) was also conducted.

Complete blood count and biochemical parameters were within normal ranges, as were most immunological tests. Elevated specific IgE levels were detected for cat allergen (41.13 kU/L), milk β-lactoglobulin (2.95 kU/L), and lamb allergen (0.41 kU/L). The ASST was positive (histamine control: 5 mm wheal with 15 mm erythema; negative control: 0 mm; patient serum: 16.5 mm wheal with 24 mm erythema). Thyroid autoantibodies, TSH, and free T4 levels were normal. Aquagenic, cold, heat, and vibration tests were negative. A positive dermographism test and a positive exercise challenge test were observed. During treadmill testing, at minute 14 after the onset of sweating, small urticarial wheals and angioedema of the lower eyelids developed. Detailed history revealed the occurrence of wheals during emotional stress and episodes of breathing difficulty during prolonged physical exertion. Based on the full diagnostic algorithm, the final diagnosis was revised to exercise-induced anaphylaxis associated with chronic spontaneous (autoimmune) and inducible (cholinergic and dermographic) urticaria, accompanied by recurrent mast cell-mediated angioedema.

This clinical case illustrates a complex combined mechanism of urticaria and angioedema involving both IgE-dependent and non-IgE-dependent pathways. It highlights the necessity of comprehensive diagnostic evaluation even when triggers appear clinically obvious. Patients with recurrent wheals should be assessed in specialized allergologіс centers with trained personnel. An apparently single trigger, such as physical exertion, may not be the sole provoking factor; combined and synergistic effects of multiple triggers are common and may be critical for patient safety. Delayed recognition of exercise-induced anaphylaxis may expose pediatric patients to life-threatening reactions.