Mast Cell Activation Syndrome

A 51-year-old woman with a history of asthma and Hashimoto's thyroiditis presented to the dermatology service with a chief complaint of "itchy bumpy rashes" that persisted beyond 24 hours. She noted that, 3 days prior to the onset of urticaria, a pyrroloquinoline quinone supplement had been started. The urticaria was accompanied by variable episodes of transient facial swelling and difficulty breathing. The patient noted that exposure to fish, nuts, and nonsteroidal anti-inflammatory drugs triggered facial swelling. Other reported findings included a 5-year history of diarrhea, sense of memory deterioration, concentration difficulties, and clinical manifestations of anomic aphasia. Although her allergy testing was "negative," she had been given the diagnoses of lactose intolerance and gastroesophageal reflux disease. Laboratory studies on initial presentation were significant for a positive history of antithyroperoxidase antibodies and elevated total complement activity. Medications included budesonide/formoterol, fluticasone/salmeterol, levothyroxine, albuterol, and fexofenadine 180 mg twice daily. Although her "rash" had initially responded to fexofenadine, it soon became refractory to treatment. Her family history was significant only for thyroid disease.