Mast cell activation disorder masquerading as a nervous breakdown

Abstract

While mast cells have been implicated in human disease since the early 1900s, mast cell activation syndrome (MCAS) was only recently discovered and recognized as a disorder caused by aberrant release of mast cell mediator enzymes. These mediators trigger a wide variety of symptoms ranging from headache, pruritis and gastrointestinal discomfort to life-threatening anaphylaxis. MCAS is frequently unrecognized and misdiagnosed because symptoms associated with MCAS are often present in other medical conditions and are highly variable among patients. We describe a case of a 62-year-old male who presented to the emergency department (ED) with three days of recurrent flushing, diarrhea, mild edema of his hands bilaterally, and severe emotional lability with recurrent crying. In the ED, he was misdiagnosed with severe anxiety and directly sent to a mental health clinic for assistance. However, he was previously seen in allergy clinic for suspected MCAS. Fortuitously standing labs including plasma histamine, tryptase, and urine studies that were ordered in allergy clinic were drawn concurrently with the initial ED workup. He was found to have elevated histamine level during his ED episode and treatment for MCAS was initiated. In subsequent visits, his symptoms, except for episodes of “brain fog” and emotional lability, improved significantly on a combination of antihistamines, oral cromolyn sodium, and montelukast. Additionally every other day prednisone has substantially cleared the neurocognitive symptoms. This case highlights the difficulty of MCAS diagnosis and the importance of assessing for MCAS, especially in patients who have multisystem complaints.