When Variants Collide: An Unusual Presentation of Metastatic Gastric Mixed Neuroendocrine-Non-Neuroendocrine Neoplasm.

ABSTRACT

Gastrointestinal neuroendocrine neoplasms were recently reclassified into the 2019 World Health Organization schema into well-differentiated neuroendocrine tumors, poorly differentiated neuroendocrine carcinomas, and mixed neuroendocrine-non-neuroendocrine neoplasms (MiNENs). Among these, gastric MiNENs are exceedingly rare and often metastasize quickly without diagnostic clues. We present a refractory gastric MiNEN with unique presenting features. This case highlights the clinical spectrum of these tumors, the importance of accurate histochemical interpretation, and clinical management in the absence of formalized guidelines. Future therapies looking at novel targets and palliative symptom relief are needed.