A woman lived with undiagnosed indolent systemic mastocytosis (SM) that caused chronic abdominal pain for more than 10 years before the disease was finally identified, according to a case report recently published in the American Journal of Gastroenterology.
“Indolent systemic mastocytosis (ISM), a subtype of systemic mastocytosis, should be considered in the differential diagnosis of patients with persistent GI symptoms refractory to medical treatment,” the authors said.
What are the types of SM?
There are five subtypes of SM: indolent SM, the most common and least severe subtype; smoldering SM, which can progress to more serious illness; aggressive SM; SM with an associated hematologic neoplasm; and mast cell leukemia, the rarest and most severe subtype.
They added: “This case underscores the diagnostic challenges of ISM in patients with chronic GI symptoms post-bariatric surgery. It highlights the necessity of a thorough clinical evaluation and consideration of ISM in differential diagnoses.”
Read more about SM testing and diagnosis
The case involved a 29-year-old woman with a history of recurring diarrhea, abdominal pain and rashes since age 16, triggered by foods, physical exercise and stressful situations. She received symptomatic treatment with pantoprazole for years. After undergoing bariatric surgery, her symptoms progressed.
Her lab work was unremarkable, and she had normal serum tryptase levels, a laboratory parameter often elevated in patients with SM. A colonoscopy revealed significant inflammation in the intestinal mucosa. A pathologic examination of the biopsy samples taken at the colonoscopy revealed an excessive population of mast cells and eosinophils throughout the intestinal tissue.
Subsequent immunohistochemical analysis was positive for CD117-positive cells and stained positive for CD25, two markers associated with SM. Financial constraints prevented genetic testing, but in light of the findings, she started treatment with omalizumab and experienced clinical improvement.
“The positive response to omalizumab therapy after inadequate response to other treatments demonstrates the potential effectiveness of targeted biologic therapy in managing ISM,” the study authors said.
Excessive mast cell release of prostaglandins in patients with SM can significantly affect gastrointestinal mobility and acid secretion. It can also produce significant inflammation in intestinal and gastric tissue.
Patients with SM often experience vomiting, heartburn, intermittent diarrhea, abdominal pain and difficulty swallowing (dysphagia). These symptoms are also present in many other clinical conditions, so a high SM awareness and suspicion is needed to make an accurate diagnosis.
