Mastocytosis is a rare disorder that results from the clonal proliferation of abnormal mast cells which accumulates in the skin and extracutaneous organs. Its prevalence is estimated at 1 in 10,000 persons. Cutaneous mastocytosis occurs in less than 5% of adults while adult-onset mastocytosis is suggestive of systemic progression. Involvement of the gastrointestinal tract occurs in 14-85% of patients diagnosed with systemic mastocytosis. This case involves a 72-year-old female previously diagnosed with cutaneous mastocytosis who presented with gastrointestinal symptoms fifteen years later. Workups done included CT scan, colonoscopy, and bone marrow aspiration. Colonic and bone marrow tissue samples revealed eosinophilia with CD117 positivity. The patient was started on therapy with imatinib. No recurrence of hematochezia was observed on follow-up.