In the Edmondson–Steiner grading system for hepatocellular carcinoma, which histological feature is characteristic of Grade III tumors?

Explanation

## Edmondson–Steiner Grading System for HCC **Key Point:** The Edmondson–Steiner grading system is a four-tier histological classification that predicts prognosis in hepatocellular carcinoma. Grade III represents moderately-to-poorly differentiated tumors characterized by **marked nuclear pleomorphism, high mitotic activity, and significant loss of differentiation** — but still retaining some recognizable hepatocellular features (unlike Grade IV). ### Edmondson–Steiner Grades | Grade | Differentiation | Nuclear Features | Mitotic Activity | Prognosis | |-------|-----------------|------------------|------------------|-----------| | I | Well-differentiated | Minimal pleomorphism, small nuclei | Very low | Excellent | | II | Moderately differentiated | Mild-to-moderate pleomorphism, larger nuclei | Low-moderate | Good | | III | Moderately-to-poorly differentiated | **Marked pleomorphism**, prominent nucleoli | **High** | Fair-Poor | | IV | Undifferentiated | Severe pleomorphism, giant cells | Very high | Poor | **High-Yield:** Grade III tumors show **marked nuclear pleomorphism and high mitotic activity with significant loss of differentiation**, distinguishing them from Grade II (moderate differentiation, mild pleomorphism) and Grade IV (completely undifferentiated, no recognizable hepatocellular features). Option D ("moderate differentiation with some nuclear irregularity and increased mitotic figures") correctly describes **Grade II**, not Grade III. **Clinical Pearl:** Grading is an independent prognostic factor in HCC. Grade III and IV tumors have significantly worse 5-year survival rates compared to Grade I and II tumors. Combined with TNM staging, grading guides treatment decisions including surgical resection candidacy and adjuvant therapy. **Mnemonic:** **Grade III = "Three strikes"** — Marked pleomorphism + High mitoses + Loss of differentiation (but not completely undifferentiated like Grade IV). *Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.; Edmondson HA, Steiner PE. Primary carcinoma of the liver. Cancer. 1954.*