Introduction

A 63-year-old woman arrives with abdominal pain, vomiting, and intermittent diarrhea. She has a history of diabetes, hypertension, and GERD. At first glance, this may appear to be common gastroenteritis, medication-related gastritis, or peptic ulcer disease. But advanced medical imaging, laboratory evaluation, and nuclear medicine reveal a much rarer cause: gastrinoma with local metastatic lymph node causing Zollinger-Ellison syndrome (ZES).

This case highlights one of the most important truths in radiology interpretation and CT scan diagnosis: common symptoms can hide uncommon disease.

Gastrinoma is a rare neuroendocrine tumor that secretes gastrin, causing uncontrolled gastric acid production. The result can be recurrent ulcers, severe diarrhea, intestinal inflammation, and life-threatening complications. Detecting these tumors requires high clinical suspicion and modern imaging such as contrast CT, MRI, endoscopy, and 68Ga-DOTATATE PET/CT.

For clinicians, radiologists, and informed readers, this guide explains everything you need to know.

Key Takeaways

Gastrinoma is a rare neuroendocrine tumor that secretes gastrin.
It causes Zollinger-Ellison syndrome, marked by excessive acid production.
Patients often present with recurrent ulcers, abdominal pain, diarrhea, or refractory GERD.
CT imaging may show bowel wall thickening, hyperenhancement, or small masses.
68Ga-DOTATATE PET/CT is highly sensitive for localization.
Duodenal gastrinomas are often smaller than pancreatic lesions.
Local lymph node metastasis may still carry a better prognosis than liver spread.
Early diagnosis can dramatically improve outcomes.

What Is Gastrinoma?

Gastrinoma is a gastrin-secreting neuroendocrine tumor (NET) most commonly found in the duodenum or pancreas. Excess gastrin stimulates parietal cells in the stomach, causing extreme acid secretion.

That acid overload damages the gastrointestinal tract and creates:

Multiple peptic ulcers
Refractory GERD
Jejunal ulcers
Chronic diarrhea
Malabsorption
Weight loss
GI bleeding

When this syndrome is caused by gastrinoma, it is called Zollinger-Ellison syndrome (ZES).

Zollinger-Ellison syndrome

Epidemiology

Gastrinoma is uncommon but clinically significant.

Important Facts

Feature	Data
Incidence	Rare
Common Age	40–60 years
Sex	Slight male predominance in some series
Location	Duodenum > Pancreas
MEN1 Association	20–30%

Many tumors are small and difficult to detect, especially in the duodenum.

Pathophysiology

Normal gastrin helps regulate digestion. Gastrinoma disrupts this control.

$\text{Tumor Gastrin} \uparrow \Rightarrow \text{Parietal Cell Acid Output} \uparrow \Rightarrow \text{Ulcers + Diarrhea}$

Biological Cascade

The tumor secretes gastrin autonomously
Gastric acid production rises sharply
Duodenal and jejunal mucosa become injured
Ulcers form repeatedly
Pancreatic enzymes become inactivated by acid
Fat malabsorption and diarrhea develop

Clinical Presentation

Symptoms vary, which often delays diagnosis.

Typical Symptoms

Burning epigastric pain
Nausea and vomiting
Chronic diarrhea
Recurrent ulcers
Weight loss
Acid reflux despite treatment
GI bleeding

In This Case

The patient presented with:

Abdominal pain
Vomiting
Intermittent diarrhea

These symptoms were clues to a hypersecretory state rather than simple infection.

Imaging Findings: CT Scan Diagnosis

Figure 1. Axial CT Abdomen/Pelvis

Caption: Axial contrast-enhanced CT demonstrates marked thickening involving the stomach, duodenum, and proximal jejunum with mucosal hyperenhancement and mild surrounding inflammatory change.

Radiology Interpretation: These findings suggest severe acid-related enteritis, ulcer disease, or inflammatory injury rather than isolated infection. The distribution strongly supports hypersecretory pathology.

Figure 2. Coronal CT Reconstruction

Caption: Coronal CT images better demonstrate contiguous involvement of upper gastrointestinal bowel loops and mural edema.

Radiology Interpretation: Coronal reformats are valuable for defining the extent of disease and identifying subtle masses in the gastrinoma triangle.

Why CT Matters in Gastrinoma

Modern multiphasic CT scan diagnosis remains essential because it can detect:

Hypervascular pancreatic NETs
Enlarged lymph nodes
Liver metastases
Bowel complications
Perforation or bleeding risks

Even when the primary tumor is tiny, secondary changes may be the first clue.

PET/CT Imaging: Functional Tumor Detection

Figure 3. 68Ga-DOTATATE PET/CT

Caption: PET/CT demonstrates two foci of increased tracer uptake: one corresponding to a 1 cm duodenal soft tissue lesion and another matching a nearby 1 cm lymph node.

Radiology Interpretation: This pattern strongly supports a somatostatin receptor-positive neuroendocrine tumor with local nodal metastasis.

Why 68Ga-DOTATATE Is Powerful

68Ga-DOTATATE binds somatostatin receptor subtype 2, commonly expressed by NETs.

Somatostatin receptor 2

Physiologic Uptake Often Seen In:

Spleen
Liver
Kidneys
Adrenal glands
Pituitary
Salivary glands

Usually Not Significant Physiologic Uptake:

Heart

Diagnosis Workflow

Step 1: Clinical Suspicion

Recurrent ulcers + diarrhea + refractory GERD = investigate hypergastrinemia.

Step 2: Laboratory Tests

Fasting serum gastrin
Gastric pH
Chromogranin A
MEN1 evaluation when appropriate

In this case, the gastrin level was 1154, more than 10 times the upper normal limit.

Step 3: Endoscopy

EGD revealed multiple nonbleeding cratered duodenal and jejunal ulcers.

Step 4: Localization Imaging

Contrast CT
MRI
Endoscopic ultrasound
68Ga-DOTATATE PET/CT

Step 5: Histology / Surgical Confirmation

Definitive diagnosis is based on pathology.

Differential Diagnosis

When CT shows upper bowel thickening and ulceration, consider:

Category	Examples
Infectious	Enteritis, CMV, H. pylori-related disease
Medication	NSAID injury
Vascular	Ischemia
Inflammatory	Crohn disease
Endocrine	Gastrinoma
Neoplastic	NET, lymphoma

This broad differential was specifically emphasized in the source case.

Treatment

Medical Management

First-line symptom control:

High-dose proton pump inhibitors
Fluid/electrolyte correction
Nutrition support

Omeprazole
Pantoprazole

Definitive Therapy

Surgical resection of localized disease
Lymph node dissection when indicated

Advanced Disease Options

Somatostatin analogs
Targeted therapy
PRRT (peptide receptor radionuclide therapy)
Liver-directed therapy for hepatic metastases

Octreotide
Lutetium Lu 177 dotatate

Prognosis

Outcome depends on stage and spread.

Better Prognosis

Small localized tumor
Isolated lymph node metastasis
Complete surgical removal

Worse Prognosis

Liver metastases
Multifocal MEN1 disease
Delayed diagnosis

The uploaded case notes that liver metastasis worsens prognosis, while isolated nodal spread may fare better.

Clinical Storytelling: Why This Case Matters

This patient looked like many others with abdominal pain and vomiting. But the persistence of symptoms, intermittent diarrhea, and extensive ulcers triggered deeper evaluation.

Without advanced medical imaging, she may have been repeatedly treated for “gastritis” while the tumor progressed silently.

That is why rare diseases matter in emergency diagnosis.

FAQ Section

Can a gastrinoma be missed on routine CT?

Yes. Many duodenal gastrinomas are under 1 cm and are difficult to see directly.

Is diarrhea common in Zollinger-Ellison syndrome?

Yes. Excess acid impairs digestion and injures bowel mucosa.

Is gastrinoma cancer?

Many gastrinomas are potentially malignant NETs. Some metastasize to the lymph nodes or liver.

What is the best imaging test?

68Ga-DOTATATE PET/CT is highly sensitive for somatostatin receptor-positive NET localization.

Is surgery curative?

It can be, especially in localized disease.

Quiz

Question 1. Which symptom combination should raise suspicion for gastrinoma?

A. Fever and cough
B. Recurrent ulcers with diarrhea
C. Hematuria
D. Headache only
E. Rash

Correct Answer: B. Explanation: Recurrent ulcers plus diarrhea strongly suggest acid hypersecretion from gastrinoma.

Question 2. What receptor does 68Ga-DOTATATE primarily target?

A. Dopamine
B. HER2
C. Somatostatin receptor 2
D. Serotonin
E. EGFR

Correct Answer: C. Explanation: DOTATATE binds somatostatin receptor subtype 2 expressed by many NETs.

Question 3. Which metastatic site usually carries the worst prognosis?

A. Local lymph node
B. Skin
C. Liver
D. Spleen
E. Thyroid

Correct Answer: C. Explanation: Hepatic metastases are associated with worse survival.

Summary Table

Topic	Key Point
Disease	Gastrinoma
Syndrome	Zollinger-Ellison syndrome
Symptoms	Pain, diarrhea, ulcers
Best Functional Imaging	68Ga-DOTATATE PET/CT
CT Clues	Bowel thickening, hyperenhancement
Treatment	PPI + surgery
Poor Prognostic Factor	Liver metastasis

Gastrinoma With Local Metastatic Lymph Node Causing Zollinger-Ellison Syndrome: CT Imaging, PET Diagnosis