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Internal Medicine


Here we present a case of chronic intractable vomiting and diarrhea of unknown cause, and introduce the relatively new entity of mast cell gastroenteritis.

Our patient is a 38-year old female with PMH of seronegative rheumatoid arthritis, mixed connective tissue disorder, and several recent hospitalizations over the past 4 months at outside hospitals for suspected colitis with associated vomiting and diarrhea. Current symptoms include 4 days of nausea with intractable vomiting, and 2 days of rectal fullness with mucoid rectal discharge. Previous workup at outside hospitals included multiple abdominal CT scans, flexible sigmoidoscopy, colonoscopy, and exploratory laparotomy. Prior to admission no definitive diagnosis were identified for her symptoms, despite extensive workup. Possible causes considered include inflammatory bowel disease, irritable bowel disease, hereditary angioedema, and small vessel vasculitis.

On admission, our physical exam showed no abnormalities including normal rectal exam. CT scan showed inflammation in the colon particularly in the rectum. A flexible sigmoidoscopy showed only edematous appearance of the colon without bleeding, ulcerations, or erythema. Biopsies were obtained, and initial pathology was non-specific. Special stains of the rectal tissue showed increased CD117+ cells at the lamina propria suggesting mast cell gastroenteritis (MCG) as the cause of her symptoms. She was treated with IV steroids until she could tolerate oral budesonide on discharge.

MCG is defined as the abundance of mast cells at the lamina propria along the GI tract. Release of inflammatory mediators by these cells cause gastrointestinal mucosal inflammation leading to symptoms of nausea, vomiting, diarrhea, and abdominal pain. The relatively new and evolving diagnosis of MCG can be part of a larger systemic process or as the patient’s primary problem. Treatments include antihistamines, cromolyn, and steroids. Knowing when to test for MCG and how to interpret the results given a clinical scenario can be helpful in understanding the cause of a patient’s symptoms. In the setting of this case we can better understand this clinical reasoning behind MCG and more effectively treat our patient and her underlying GI mastocytosis.


Internal Medicine


Graduate Medical Education

Conference / Event Name

Academic Achievement Day, 2020


Providence Portland Medical Center, Internal Medicine Residency, Portland, Oregon

A Perplexing Case Of Episodic Abdominal Pain And The Role Of Mast Cells Gastroenteritis