Case Presentation: A 41-year-old Hispanic woman with a past medical history of intractable trigeminal neuralgia and recurrent admissions for associated facial and airway swelling requiring intubation presented with acute onset of severe facial and tongue swelling, dyspnea, and neuropathic facial pain, similar to prior flare-up episodes. A pruritic rash on the chest and bilateral hand swelling were also present, and she reported a history of systemic symptoms including hand swelling, abdominal pain, and nausea during previous episodes. A previous extensive workup was negative for mastocytosis or hereditary angioedema. She received intramuscular epinephrine with symptom improvement and was monitored in the ICU for unstable airway, but did not require intubation. She improved with antihistamine and steroid treatment and narcotic pain management. A 24-hour urine study on hospital day five revealed elevated levels of leukotriene E4 consistent with MCAS, but normal levels of N-methylhistamine and 2,3-Dinor-11beta-prostaglandin F2 alpha. She was discharged on an antihistamine trial with outpatient follow-up for ongoing workup and treatment.
Discussion: Mast cell activation syndrome (MCAS) is characterized by recurrent episodes of symptoms due to inappropriate release of mast cell mediators, which improve with anti-mediator therapies. MCAS is a fairly newly recognized condition, first proposed as a distinct disorder in 2010 with subsequent establishment of generally accepted diagnostic criteria. Diagnosis can prove challenging due to the high variability in presentation and the precise timing of diagnostic studies required. Based on episodic symptoms consistent with mast cell activation involving at least two organ systems, elevation of a validated urinary marker of mast cell activation during a symptomatic episode, and improvement with anti-mediator therapy, our patient met proposed criteria for diagnosis of MCAS; however the presence of other urinary markers in the normal range and lack of baseline data made her diagnosis ambiguous. Furthermore, while multiple studies have suggested an association between mast cell disorders and activation of neuropathic pain pathways, to our knowledge no cases of MCAS associated with trigeminal neuralgia have been reported. The present case demonstrates a number of the diagnostic challenges of MCAS and illustrates a potential unique neurologic presentation of this disorder.
Conclusions: Diagnostic workup for MCAS includes identification of temporally sensitive testing at the onset of symptoms. It is pertinent to recognize trigeminal nerve pain as a rare but physiologically plausible presenting symptom of MCAS.