A 40-year-old patient with hypertension, hypokalemia, and suppressed renin has an adrenal adenoma on CT. Adrenal vein sampling shows a lateralization ratio of >4:1 favoring the left side. Histology of the surgically removed adenoma shows lipid-rich clear cells with mild nuclear atypia. The Weiss criteria for adrenocortical carcinoma requires at least 3 of 9 features. Which feature, if present alone, is most predictive of malignancy?
- A Vascular invasion (invasion of endothelium-lined vascular spaces in the capsule/outside) ✓
- B Diffuse architecture (>1/3 of tumor)
- C High nuclear grade (Fuhrman grade 3–4)
- D Mitotic rate >5 per 50 HPF
Explanation
Among the Weiss criteria for adrenocortical carcinoma, vascular invasion (defined as tumor cells within endothelium-lined vascular spaces with adherent thrombus, in capsular or extra-adrenal vessels) is considered the most specific single criterion for malignancy. It indicates true malignant behavior with metastatic potential. While the modified Weiss system weights capsular invasion and atypical mitoses most highly, unequivocal vascular invasion has the strongest individual predictive value for malignancy. Diffuse architecture and high nuclear grade can occasionally be seen in adenomas. The Lin-Weiss-Bisceglia criteria uses vascular invasion as a major criterion sufficient alone for malignancy.
Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.
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Written and medically reviewed by the StethoPrep medical team.