In evaluating a suspected RCC, what CT feature suggests a malignant mass?

• A. Uniform enhancement
• B. Irregular, heterogeneous enhancement with possible necrosis after contrast
• C. No enhancement
• D. Calcifications only

Answer: (B)

On contrast-enhanced CT, malignant renal masses like RCC tend to show irregular, heterogeneous enhancement because the tumor has uneven blood flow and areas of necrosis or hemorrhage. Those necrotic regions do not enhance, creating a mix of enhancing and non-enhancing areas within the same mass. This heterogeneous pattern is a key clue to malignancy. In contrast, a mass that enhances uniformly suggests a more benign lesion with consistent vascularity, no enhancement points to a simple cyst, and calcifications can occur but by themselves do not define malignancy. Therefore, irregular, heterogeneous enhancement with possible necrosis after contrast best indicates a malignant mass.