Pancreatic neuroendocrine tumor presenting in indolent systemic mastocytosis: A case report

INTRODUCTION: Systemic mastocystosis, a disorder of clonal mast cell expansion presents with symptoms of flushing, pruritus, musculoskeletal pain, gastrointestinal cramping and vascular instability. Patients with neuroendocrine tumors may present with similar symptoms due to the release of vasoactive mediators in both diseases. We report the co-occurrence of systemic mastocytosis and a neuroendocrine pancreatic tumor for which the patient received disease-specific treatment. CASE PRESENTATION: A 58-year-old woman with a history of indolent systemic mastocytosis and a serum tryptase of 51 ng/mL was diagnosed with a solid pancreatic lesion on ultrasound when assessing for organomegaly. Lesional biopsy was consistent with a pancreatic neuroendocrine tumor which was successfully resected. DISCUSSION: Presenting symptoms such as skin rashes, flushing, fatigue and diarrhea, are similar for systemic mastocytosis and neuroendocrine tumors. The co-occurrence of both diseases has not been previously reported. Activating mutations in KIT, which are a hallmark of systemic mastocytosis, may drive neoplastic proliferation in neuroendocrine tumors. Furthermore, mast cells infiltrating pancreatic tissue may have a trophic effect on the development of pancreatic neuroendocrine tumors. CONCLUSION: While challenging to diagnose both diseases presenting with similar symptoms, recognition of these distinct diseases is necessary to ensure timely treatment.