Unusual Upper Gastrointestinal Bleeding Due to a Neuroendocrine Tumor Arising in Meckel Diverticulum.

Meckel diverticulum is the most common congenital variation of the gastrointestinal tract arising from incomplete obliteration of the vitelline duct during gestation. In most cases, individuals are asymptomatic. This is a case of a 38-year-old patient with hematochezia in whom Meckel diverticulum was diagnosed. A mass was identified within the diverticulum. Histopathological and immunohistochemical studies revealed a well-differentiated neuroendocrine tumor. The development of tumors in Meckel diverticulum is rare, and when identified, only 0.5%-3.2% of these tumors are found to be malignant. Furthermore, gastrointestinal bleeding is an infrequent clinical feature of neuroendocrine tumors. A unique aspect of this case was that numerous imaging studies and endoscopic procedures were unable to definitively identify the presence of Meckle diverticulum and underlying neuroendocrine tumor. Through a high clinical suspicion and collaboration with surgical colleagues, an exploratory laparotomy was performed, which ultimately led to the identification and diagnosis of the underlying pathology.