Indolent Systemic Mastocytosis: An Incidental Diagnosis

Indolent systemic mastocytosis (ISM) is the most prevalent subtype of systemic mastocytosis, characterized by a clinical course progressing over several years to decades. We present a case of a 57-year-old woman with symptoms of flushing and occasional dizziness who was diagnosed with ISM after a colon polyp biopsy revealed CD3-, CD20-, and CD25-positive atypical mast cell infiltrates. The patient was started on antihistamines with advice to avoid triggering factors. This case raises awareness about mast cell disorders. Clinicians should always keep these disorders in mind while evaluating a patient with nonspecific signs and symptoms involving multiple organ systems.