Complex Presentations, Identification and Treatment of Mast Cell Activation Syndrome and Associated Conditions: A Case Report.

Mast Cell Activation Syndrome (MCAS) is only a recently recognized, multisystem disorder that has been historically underrecognized due its estimated high prevalence. Recognition, testing, and treatment all pose unique challenges to condition management. The condition warrants more concern due to its prevalence and under recognition. Of equal importance in this case is the overlap seen between conditions such as MCAS, gastric dysmotility often manifesting as small intestine bacterial overgrowth (SIBO), dysautonomia, joint hypermobility disorders such as hypermobile Ehlers Danlos Syndrome (h-EDS) or other hypermobility spectrum disorders (HSD), and autoimmunity. This case involves a 42 year-old female who initially presented to the clinic for chronic SIBO and associated gastrointestinal complaints. Upon further examination into the patient's history and unique presentation as visits progressed, important factors affecting treatment considerations were discovered. The patient was ultimately deemed to have other associated conditions including a mast cell-mediated disorder as well as joint hypermobility due to her response to antihistamine and mast cell stabilizing agents. Final outcomes include immense improvement upon mast cell stabilization with ketotifen, and remission of SIBO with low-dose naltrexone (LDN). Although the patient did not undergo testing beyond a serum tryptase test, this case represents the importance of careful history taking and the role of clinical suspicion on patient outcomes.