A Case of Systemic Mastocytosis Diagnosed Endoscopically

Mastocytosis, or mast cell proliferation, is very rare. Overall, 60% of patients with systemic mastocytosis (SM) have gastrointestinal involvement, with the colon being the most prevalent affected site. Most patients are diagnosed by bone marrow biopsy. Although gastrointestinal symptoms are common, patients are rarely diagnosed via endoscopy. Indolent SM, which is characterized by both gastrointestinal and cutaneous symptoms in the absence of bone marrow suppression, is extremely rare and often missed due to the complexity of the diagnosis. Here, we present the case of a patient with abdominal pain, flushing, and nausea who was diagnosed endoscopically with SM, likely the indolent type.