A patient with adrenal cortical carcinoma (ACC) has a mass showing 9 mitoses per 10 HPF, atypical mitoses, venous invasion, fibrous bands, and necrosis. Using the Weiss scoring system, what score does this tumour receive and what does it mean?
- A Weiss score 4 (≥5 mitoses + atypical mitoses + venous invasion + necrosis) — a score ≥3 defines adrenocortical carcinoma; scores ≥6 indicate the most aggressive behaviour ✓
- B Weiss score 1 — only necrosis applies; the mitosis threshold is 20 per HPF for malignancy
- C The Weiss system does not apply to adrenocortical tumours; Ki-67 index >10% alone defines ACC
- D Weiss score 2 — fibrous bands and necrosis score 2; malignancy requires a score ≥5
Explanation
The Weiss scoring system for adrenocortical tumours evaluates 9 histological criteria: (1) high nuclear grade (Fuhrman 3/4), (2) mitotic rate >5/50 HPF (here 9 mitoses/10 HPF = markedly elevated), (3) atypical mitoses, (4) clear cells ≤25%, (5) diffuse architecture >33%, (6) necrosis, (7) venous invasion, (8) sinusoidal invasion, (9) capsular invasion. A score ≥3 is diagnostic of adrenocortical carcinoma. This tumour scores at least 4 (≥5 mitoses, atypical mitoses, venous invasion, necrosis) from the criteria described, unambiguously classifying it as ACC. The Weiss system remains the standard though modifications (modified Weiss, Helsinki score, Lin-Weiss-Bisceglia for oncocytic tumors) exist.
Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.
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