Adenocarcinoma of the First Part of the Duodenum: Causes, Pathophysiology, Imaging Features, and Treatment

Introduction

Adenocarcinoma of the first part of the duodenum is a rare but clinically significant gastrointestinal malignancy that often presents with vague symptoms, leading to delayed diagnosis.

Despite being an uncommon tumor, its clinical implications are profound due to the anatomical complexity of the duodenum and its proximity to critical structures such as the pancreas, bile duct, and stomach.

In this column, I will explore the etiology, pathophysiology, epidemiology, clinical features, imaging findings, treatment strategies, and prognosis of this condition, referencing a real-world clinical case of a 39-year-old male with chronic abdominal pain diagnosed with duodenal adenocarcinoma.

Case Background

A 39-year-old man presented with chronic abdominal pain and acute epigastric discomfort.

He had a past medical history of Crohn’s disease and anal stricture.

Imaging studies, including CT, MRI, and fluoroscopy, revealed a suspicious mass in the first part of the duodenum (duodenal bulb), later confirmed as adenocarcinoma of the duodenum through endoscopic biopsy.

Imaging Figures

Figure 1. Axial CT – Shows ill-defined soft tissue density in the duodenal bulb.

Figure 2. Coronal CT – Demonstrates a mass effect within the duodenal lumen.

Figure 3. MRI DWI – Restricted diffusion corresponding to the duodenal mass.

Figure 4. MRI ADC – Confirms diffusion restriction.

Figure 5. Normal Upper GI series – Reference image for comparison.

Figure 6. Upper GI fluoroscopy with duodenal cancer – 3 cm circumferential mass with shelf-like margins and ulceration.

Etiology and Causes

Duodenal adenocarcinoma arises from the glandular epithelial cells lining the mucosa of the duodenum. Although rare, several risk factors have been identified:

Chronic Inflammation
- Crohn’s disease, particularly with duodenal involvement, predisposes to malignant transformation.
Genetic Syndromes
- Familial adenomatous polyposis (FAP)
- Lynch syndrome (HNPCC: Hereditary Non-Polyposis Colorectal Cancer)
- Peutz-Jeghers syndrome
Celiac disease – Chronic inflammatory injury may lead to neoplastic transformation.
Dietary and Environmental Factors – High intake of red meat, smoking, and alcohol consumption are suggested risk factors.

Pathophysiology

Duodenal adenocarcinoma develops through a sequence of mucosal dysplasia → adenoma → carcinoma, similar to colorectal carcinogenesis.

The first part of the duodenum (duodenal bulb) is exposed to gastric acid and bile, making it susceptible to chronic irritation.
Mutations in the APC, KRAS, and p53 genes are frequently implicated.
Local invasion occurs early due to the thin duodenal wall and close proximity to vital structures, leading to early obstruction or metastasis.

Epidemiology

Small bowel tumors represent only 1–2% of gastrointestinal malignancies, yet adenocarcinoma accounts for 40% of small bowel cancers.
Approximately 50% of small bowel adenocarcinomas occur in the duodenum, but only 15% involve the first part.
Peak incidence is seen in the 6th decade of life, but cases may present earlier in those with genetic syndromes or Crohn’s disease.
Men are affected slightly more than women.

Clinical Presentation

Duodenal adenocarcinoma often presents with nonspecific symptoms, contributing to delayed diagnosis:

Chronic abdominal pain
Nausea, vomiting, indigestion
Weight loss and fatigue
Iron-deficiency anemia (due to occult bleeding)
Obstructive symptoms (gastric outlet obstruction)
Jaundice (if the tumor invades the ampullary region or the bile duct)
Perforation or bleeding in advanced disease

Imaging Features

1. Computed Tomography (CT)

Primary modality of choice for evaluation.
Findings:
- Circumferential duodenal mass with shelf-like margins.
- Moderate enhancement with contrast.
- Possible ulceration.
- Adjacent fat stranding or invasion into nearby structures.

📌 Figure 1 & Figure 2 illustrate typical CT findings.

2. Magnetic Resonance Imaging (MRI)

Not first-line, but useful for liver metastasis evaluation.
DWI/ADC mapping shows restricted diffusion in malignant lesions.

📌 Figure 3 & Figure 4 demonstrate MRI features.

3. Upper GI Fluoroscopy

Classic findings: shelf-like filling defects, mucosal irregularity, ulceration.
May demonstrate partial obstruction with fluid stasis.

📌 Figure 5 & Figure 6 compare normal vs. pathological findings.

4. Endoscopy (EGD)

Allows direct visualization, biopsy, and therapeutic intervention.
Essential for confirming diagnosis.

Differential Diagnosis

Pancreatic head carcinoma
Cholangiocarcinoma (distal bile duct)
Lymphoma
Metastatic lesions (from stomach or colon)

Treatment

Surgical Resection – Mainstay of therapy.
- Segmental resection for localized tumors in the first part.
- Pancreaticoduodenectomy (Whipple procedure) if extensive involvement.
Adjuvant Chemotherapy
- No standardized regimen, but fluoropyrimidine-based chemotherapy is sometimes used.
Radiotherapy
- Limited role due to small bowel radiosensitivity.
Palliative Care
- For unresectable disease: stenting, bypass surgery, or systemic chemotherapy.

Prognosis

Resectable disease: 5-year survival rate up to 40%.
Overall prognosis remains poor, with 5-year survival around 11% due to late-stage presentation.
Prognosis worsens with:
- Nodal involvement
- Distant metastasis
- Poor tumor differentiation

Quiz Section

1. What is the most appropriate next diagnostic step after CT reveals a suspicious duodenal mass?

(A) Abdominal MRI

(B) Chest CT

(D) Upper GI fluoroscopy

2. Which of the following is TRUE regarding duodenal adenocarcinoma?

MRI is the primary modality for diagnosis.
Most cases occur in the third part of the duodenum.
Crohn’s disease is a risk factor.
Chemotherapy alone is curative.

3. What is the hallmark fluoroscopic finding in duodenal adenocarcinoma?

(A) Smooth mucosal surface

(B) Shelf-like margins with a filling defect

(D) Absence of ulceration

4. What is the best treatment option for localized duodenal adenocarcinoma?

(A) Radiotherapy

(B) Endoscopic stenting

(D) Chemotherapy alone

Answer & Explanation

1. Answer: (C) EGD. Explanation: EGD allows both direct visualization and biopsy, making it superior for diagnosis.

2. Answer: (3) Crohn’s disease is a risk factor. Explanation: MRI is secondary, the first part is less common, and chemotherapy alone is not curative.

3. Answer: (B) Shelf-like margins with filling defect. Explanation: This radiographic pattern strongly suggests a neoplastic process.

4. Answer: (C) Surgical resection. Explanation: Surgery offers the best long-term survival.

References

[1] M. Barat, A. Dohan, R. Dautry, et al., “Mass-forming lesions of the duodenum: A pictorial review,” Diagn Interv Imaging, vol. 98, no. 10, pp. 663–675, 2017.

[2] J. M. Cloyd, E. George, B. C. Visser, “Duodenal adenocarcinoma: Advances in diagnosis and surgical management,” World J Gastrointest Surg, vol. 8, no. 3, pp. 212–221, 2016.

[3] M. V. Jayaraman, W. W. Mayo-Smith, J. S. Movson, D. E. Dupuy, M. T. Wallach, “CT of the duodenum: An overlooked segment gets its due,” Radiographics, vol. 21, suppl. 1, pp. S147–S160, 2001.

[4] R. Overman, “Recent advances in the management of adenocarcinoma of the small intestine,” Gastrointest Cancer Res, vol. 3, no. 3, pp. 90–96, 2009.

[5] N. Halfdanarson, M. McWilliams, F. Donohue, “Adenocarcinoma of the small bowel: Epidemiology, risk factors, and treatment,” Mayo Clin Proc, vol. 85, no. 2, pp. 183–189, 2010.

[6] C. Dabaja, A. Suki, J. Pro, “Adenocarcinoma of the small bowel: presentation, prognostic factors, and outcome of 217 patients,” Cancer, vol. 101, no. 3, pp. 518–526, 2004.

[7] M. P. Howe, A. Karnell, T. Menck, “The American College of Surgeons Commission on Cancer and the American Cancer Society national cancer data base report on adenocarcinoma of the small intestine,” Cancer, vol. 86, no. 12, pp. 2693–2706, 1999.

MediAI

Search This Blog