A solitary mastocytoma presenting with urticaria and angioedema in a 14-year-old boy.

Urticaria with angioedema is a common clinical presentation that often poses a challenge for allergists. The differential diagnosis for urticaria is broad, making the evaluation and pinpointing the underlying cause difficult and frustrating for both families and physicians. Certain causes of urticaria such as infections or medications are more common and easier to identify whereas less frequently seen conditions are often overlooked because of their rarity. One such condition is mastocytosis. Mastocytosis is a rare disease that very seldom presents with urticaria but may be associated with significant morbidity and mortality if not recognized in a timely manner. We are presenting a case of a 14-year-old boy who presented with urticaria and angioedema possibly caused by a solitary mastocytoma. The learning points from this case are that mastocytosis should be considered in the differential diagnosis of urticaria and solitary mastocytomas may remain active into adolescence, raising concern for systemic progression.