ARRT Pathology Recognition 2 — Questions and Answers
Question 1: A CT of the chest shows a 2.5 cm solitary pulmonary nodule with central 'popcorn' calcification. What is the most likely diagnosis?
- Bronchogenic carcinoma
- Hamartoma (Correct answer)
- Metastatic deposit
- Carcinoid tumor
Correct answer: Hamartoma
Popcorn calcification within a pulmonary nodule is characteristic of a pulmonary hamartoma.
Question 2: On CT pulmonary angiography, a saddle embolus is identified. Where is this embolus located?
- Right main pulmonary artery only
- Left main pulmonary artery only
- Straddling the main pulmonary artery bifurcation (Correct answer)
- Within segmental pulmonary arteries bilaterally
Correct answer: Straddling the main pulmonary artery bifurcation
A saddle embolus straddles the bifurcation of the main pulmonary artery, occluding both left and right pulmonary arteries.
Question 3: A CT abdomen reveals a liver lesion that is hypodense on non-contrast, enhances intensely on arterial phase, and becomes isodense to liver on portal venous phase. This pattern is most consistent with:
- Hepatocellular carcinoma (Correct answer)
- Hepatic hemangioma
- Cholangiocarcinoma
- Focal nodular hyperplasia
Correct answer: Hepatocellular carcinoma
Arterial hyperenhancement with washout on portal venous phase is the classic CT hallmark of hepatocellular carcinoma.
Question 4: Which CT finding is most characteristic of acute mesenteric ischemia due to superior mesenteric artery occlusion?
- Pneumatosis intestinalis (Correct answer)
- Bowel wall thickening with hyperenhancement
- Ascites alone
- Retroperitoneal hematoma
Correct answer: Pneumatosis intestinalis
Pneumatosis intestinalis (gas within the bowel wall) indicates bowel infarction and is a hallmark of severe mesenteric ischemia.
Question 5: A CT head without contrast shows a hyperdense crescent-shaped collection along the inner table of the skull. This is most consistent with:
- Epidural hematoma
- Acute subdural hematoma (Correct answer)
- Subarachnoid hemorrhage
- Intraparenchymal hematoma
Correct answer: Acute subdural hematoma
Acute subdural hematomas appear as hyperdense crescent-shaped collections that conform to the brain surface and cross suture lines.
Question 6: On CT urography, a urothelial carcinoma of the ureter would most likely appear as:
- Smooth fusiform dilation of the ureter
- Intraluminal filling defect with upstream hydronephrosis (Correct answer)
- Periureteral fat stranding only
- Ureteral wall calcification
Correct answer: Intraluminal filling defect with upstream hydronephrosis
Urothelial carcinoma typically presents as an intraluminal filling defect causing partial or complete obstruction with upstream hydronephrosis.
Question 7: Which CT finding helps differentiate a retroperitoneal hematoma from a retroperitoneal abscess?
- Location posterior to the peritoneum
- Presence of gas bubbles within the collection
- Hyperdense content on non-contrast CT (Correct answer)
- Displacement of adjacent organs
Correct answer: Hyperdense content on non-contrast CT
Acute hematomas appear hyperdense (50–70 HU) on non-contrast CT due to clotted blood, distinguishing them from fluid collections.
ARRT Pathology Recognition 2
A CT of the chest shows a 2.5 cm solitary pulmonary nodule with central 'popcorn' calcification.
What is the most likely diagnosis?