Duodenal adenocarcinoma is the most common primary malignancy of the duodenum.
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Epidemiology
Adenocarcinoma is the most common primary malignant neoplasm of the duodenum. It represents 0.3% of all gastrointestinal malignancies and accounts for 50-70% of small bowel adenocarcinomas occurring either in the duodenum or proximal jejunum.
The peak incidence is in the 7th decade. More than 50% of them have metastases at the time of diagnosis 1.
Clinical presentation
Most of the clinical features are non-specific and include upper abdominal pain and weight loss as the most common presenting symptoms. In the late phases of the disease, a variety of symptoms and signs have been reported, such as symptoms of proximal intestinal obstruction and jaundice, hematemesis, melena, and fecal occult blood. A variety of other findings, such as low back pain and alteration in bowel habits, have also been described.
Pathology
Grossly they have a napkin ring appearance or appear as a polypoid fungating mass.
Risk factors
syndromic, e.g. familial adenomatous polyposis, Gardner syndrome, Lynch syndrome, Peutz-Jeghers syndrome 2,10
inflammatory, e.g. Crohn disease, celiac disease 10
duodenal polyps without a predisposing family history 2
Location
distal portion (3rd and 4th parts): 45%
second part: 40%
first part: 15%
Radiographic features
Fluoroscopy
According to some publications, upper GI series is the most accurate diagnostic modality for small-bowel carcinomas 3. Upper GI shows features of mucosal pattern distortion, obliteration and narrowing. Delayed images may show barium holdup at the site of the lesion 4.
Ultrasound
The lesions appear as irregularly hypoechoic masses. Ultrasonography can diagnose and assess the vascularity of larger lesions but the smaller tumors (<2 cm) may not be detected 2.
CT
CT is the modality of choice for the staging of the disease by identifying the primary tumor and assessing local, nodal, and distant spread 3,5.
Demonstration of lesions facilitated by negative contrast agents (water):
intrinsic mass with a short segment of bowel wall thickening 6
invasion of retroperitoneal fat planes, pancreatic and biliary duct, vascular encasement, lymph nodal and distant metastases is common in later stages 7
Treatment and prognosis
Duodenal adenocarcinoma is associated with a delayed diagnosis and poor prognostic and survival outcomes due to non-specific clinical presentation.
Metastasis, poor tumor differentiation, increased depth of spread and pre-existing Crohn's disease are associated with poor prognosis.
Recurrence of the tumor is also a common entity. The most common sites of recurrence are the liver, lungs and peritoneum 3.
The only possibility of improving prognosis is the early diagnosis of the primary tumor, which affords a higher chance of tumor resectability 8.
Pancreaticoduodenectomy is required for tumors of the first and second portions of the duodenum. In tumors of the distal duodenum, segmental resection may be adequate 9.
Differential diagnosis
General imaging differential considerations include:
lower common bile duct tumors
regional colonic carcinoma with duodenal invasion