ARRT Pathology Recognition 3 — Questions and Answers
Question 1: A patient with known Crohn's disease undergoes CT enterography. Which finding most specifically indicates active inflammation?
- Bowel wall thickening with mural hyperenhancement and the comb sign (Correct answer)
- Non-enhancing bowel wall thickening
- Mesenteric lymphadenopathy alone
- Ascites
Correct answer: Bowel wall thickening with mural hyperenhancement and the comb sign
Active Crohn's disease shows mural hyperenhancement, wall thickening, and engorged vasa recta (comb sign) on CT enterography.
Question 2: On a non-contrast CT of the abdomen, a renal calculus most likely to be missed is composed of which material?
- Calcium oxalate
- Struvite
- Uric acid
- Indinavir (drug-related) (Correct answer)
Correct answer: Indinavir (drug-related)
Indinavir stones are radiolucent and have very low Hounsfield units, making them nearly invisible on non-contrast CT.
Question 3: A CT chest in a patient with AIDS shows bilateral ground-glass opacities in a 'bat-wing' distribution. The most likely diagnosis is:
- Cytomegalovirus pneumonitis
- Pneumocystis jirovecii pneumonia (Correct answer)
- Kaposi sarcoma
- Mycobacterium avium complex
Correct answer: Pneumocystis jirovecii pneumonia
PCP (Pneumocystis jirovecii pneumonia) classically presents with bilateral perihilar ground-glass opacities in immunocompromised patients.
Question 4: CT of the neck in a patient with a palpable mass shows a cystic lesion at the angle of the mandible deep to the sternocleidomastoid muscle. This is most consistent with:
- Thyroglossal duct cyst
- Branchial cleft cyst (Correct answer)
- Dermoid cyst
- Lymphatic malformation
Correct answer: Branchial cleft cyst
Branchial cleft cysts characteristically appear as unilocular cystic masses at the angle of the mandible adjacent to the sternocleidomastoid muscle.
Question 5: Which feature on CT best distinguishes a benign adrenal adenoma from a metastasis?
- Lesion size greater than 3 cm
- Attenuation less than 10 HU on non-contrast CT (Correct answer)
- Homogeneous enhancement pattern
- Round morphology
Correct answer: Attenuation less than 10 HU on non-contrast CT
Adrenal adenomas are lipid-rich and typically measure less than 10 HU on unenhanced CT, a reliable distinguishing feature from metastases.
Question 6: On CT angiography of the aorta, which finding is pathognomonic of an aortic dissection?
- Aortic dilation greater than 5 cm
- An intimal flap separating true and false lumens (Correct answer)
- Periaortic hematoma
- Mural thrombus
Correct answer: An intimal flap separating true and false lumens
An intimal flap creating two distinct lumens (true and false) is the defining CT finding of aortic dissection.
Question 7: A CT pelvis shows a complex ovarian mass with solid components, calcifications, fat density, and hair-like structures. This is most consistent with:
- Mucinous cystadenoma
- Serous cystadenocarcinoma
- Mature cystic teratoma (dermoid cyst) (Correct answer)
- Endometrioma
Correct answer: Mature cystic teratoma (dermoid cyst)
Mature cystic teratomas contain fat, calcium, and soft tissue elements (including teeth or hair) from multiple germ cell layers.
ARRT Pathology Recognition 3
A patient with known Crohn's disease undergoes CT enterography.
Which finding most specifically indicates active inflammation?