Challenging diagnosis of indolent systemic mastocytosis isolated to the GI tract

Mastocytosis is a rare group of disorders that presents with heterogenous phenotypes depending on the organ system involved. In the absence of cutaneous involvement-mast cell aggregates that may present as papules, nodules or plaques-classically associated with indolent systemic mastocytosis (SM), the diagnosis of this rare condition is particularly challenging. When localised to the gastrointestinal (GI) tract, symptoms of indolent SM are often non-specific and mimic common conditions such as inflammatory bowel disease or irritable bowel syndrome. Diagnosis may be suspected by clinical presentation, but biopsy with histopathological analysis is necessary to confirm. We present a rare case of indolent SM without cutaneous features. In the absence of typical cutaneous features, indolent SM should be considered in the differential diagnosis of a patient with persistent GI symptoms refractory to medical treatment, as failure to do so can lead to delay in the appropriate diagnosis and treatment.