A 32-year-old woman presents with episodic hypertension, headache, diaphoresis, and palpitations. 24-hour urine shows markedly elevated catecholamines and their metabolites. CT reveals a 4 cm right adrenal mass. Histologically, this tumor is characterized by which feature that predicts malignancy?

• A Nuclear pleomorphism and mitotic figures
• B Coagulative necrosis alone
• C Capsular invasion and vascular invasion on histology ✓
• D Cellular monotony and lack of pleomorphism

Explanation

Pheochromocytoma arises from adrenal medullary chromaffin cells. Distinguishing benign from malignant pheochromocytoma by histology alone is notoriously unreliable; nuclear pleomorphism and mitoses can be seen in benign tumors. The only reliable criteria for malignancy are metastases to non-chromaffin tissue, or histologic evidence of capsular or vascular invasion. The PASS (Pheochromocytoma of the Adrenal gland Scaled Score) system uses these features collectively.

Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.