More Than Just a Gut Feeling: Unmasking Systemic Mastocytosis Behind Chronic Gastrointestinal Symptoms in a 2-Patient Case Series.

Systemic mastocytosis is a rare clonal mast-cell disorder whose gastrointestinal manifestations may mimic common diseases and delay diagnosis. We present 2 women with longstanding gastrointestinal symptoms, including 1 treated for Crohn's disease for more than 15 years. Gastrointestinal biopsies demonstrated mast-cell infiltrates consistent with systemic mastocytosis, supported by elevated serum tryptase and KIT proto-oncogene, receptor tyrosine kinase (KIT) D816V mutations. Both received mast cell-directed therapy, with differing response and tolerability. These cases highlight the importance of considering systemic mastocytosis in refractory or atypical gastrointestinal disease, particularly when accompanied by skin or skeletal findings.