Question

All of the following statements about the CT scan features of an adrenal adenoma are true, except:

• A. Calcification is rare
• B. Low attenuation
• C. Early enhancement with slow wash out of contrast
• D. Regular margins

Hint:

Adenomas wash contrast out fast; slow washout suggests malignancy or pheochromocytoma.

Answer 1

The Correct Option is C

Step 1: This is a negative question. Three options describe true features of a benign adrenal adenoma, and one is false.
Step 2: A benign adrenal adenoma is typically a small, well-defined mass with smooth regular margins, so option D is true. Calcification is uncommon in adenomas, so option A is true.
Step 3: Most adenomas are lipid-rich, meaning they contain intracellular fat. This gives them low attenuation on unenhanced CT, classically 10 Hounsfield units or less. So option B is true.
Step 4: The defining CT behaviour of an adenoma is its contrast kinetics. An adenoma enhances and then shows rapid washout of contrast, giving a high absolute and relative percentage washout. Slow washout is the pattern seen in malignant lesions and pheochromocytoma, not adenoma. So the statement 'early enhancement with slow wash out of contrast' is false. The correct adenoma behaviour is enhancement with rapid washout.
Step 5: Since the question asks for the exception, the false statement is option C.
Answer: Option C, Early enhancement with slow wash out of contrast.