Duodenal carcinoma is a very rare tumor of the gastrointestinal tract but is one of the most common arising from the small intestine. Tumors can develop in any duodenal segment, and the nonspecific clinical presentation of gastrointestinal complaints is the primary reason why it is often recognized late and why a poor prognosis is expected in many cases. Both invasive and noninvasive imaging studies are used to confirm the diagnosis.
Duodenal carcinoma (also known as duodenal adenocarcinoma, as the tumor arises from the glandular part of the epithelium) comprises less than 1% of all tumors from the gastrointestinal (GI) tract, but up to 55% of all small intestinal adenocarcinomas originate in the duodenum, suggesting its rather important place among neoplastic tumors of the GI tract     . Tumors may arise in any of the four duodenal segments - superior (I), descending (II), inferior (III) and ascending (IV), with respective variations in terms of frequency across different reports   . The clinical presentation of duodenal carcinoma is nonspecific, which supported by the fact that abdominal pain is the principal complaint   . Accompanying features are weakness, fatigue, GI bleeding and obstruction, weight loss, jaundice, nausea and vomiting  . Unfortunately, lack of clinical suspicion toward duodenal carcinoma as a result of nonspecific symptoms is the reason why the diagnosis is often made up to 15 months after the appearance of symptoms, leading to a poorer prognosis and inability to perform surgical resection of the tumor, thus requiring more aggressive forms of chemotherapy that are heavily tolerated  . Current understanding of the pathogenesis of this tumor is incomplete, but the presence of hereditary GI tract diseases, such as familial adenomatous polyposis and Gardner syndrome, as well as history of duodenal polyps, seem to increase the risk for duodenal carcinoma  .
As mentioned previously, the nonspecific clinical presentation of duodenal carcinoma can be a significant challenge for the physician, but because early recognition dramatically improves overall survival, a meticulous workup should be carried out in all individuals with such complaints. The development of symptoms and their progression must be noted during history taking, and after a complete physical examination, imaging studies, considered as the cornerstone of diagnosis, need to be employed. Standard ultrasonography, computed tomography (CT) or magnetic resonance imaging (MRI) serve as first-line techniques   . To confirm duodenal carcinoma, esophagogastroduodenoscopy is the gold-standard in visualizing the tumor, but it is also beneficial because a biopsy sample can be obtained for histopathological examination during this procedure   . Upper endoscopic techniques may not always reach the site of the tumor, however, thus being unable to make the diagnosis unless specialized longer scopes are available . For this reason, barium radiography of the GI tract is also recommended, as it carries a very high rate of diagnosis as well  . A histological diagnosis is necessary, and together with CT/MRI findings, appropriate clinical staging of the tumor can be performed, which has critical implications for the choice of therapy.