NASH (non-alcoholic steatohepatitis) histology is scored using the NAS (NAFLD Activity Score). Which three histological features are assessed by the NAS?
- A Fibrosis stage (0–4), steatosis grade (0–3), and Mallory-Denk bodies (0–2)
- B Portal inflammation (0–3), interface hepatitis (0–3), and rosette formation (0–2)
- C Steatosis (0–3), lobular inflammation (0–3), and hepatocyte ballooning (0–2) — NAS 0–8 ✓
- D Lobular necrosis (0–3), bile duct proliferation (0–2), and perivenular fibrosis (0–2)
Correct answer: C. Steatosis (0–3), lobular inflammation (0–3), and hepatocyte ballooning (0–2) — NAS 0–8
Explanation
The NAFLD Activity Score (NAS) sums three unweighted histological features: steatosis grade (0–3: <5%, 5–33%, 33–66%, >66%), lobular inflammation (0–3), and hepatocyte ballooning (0–2), giving a maximum of 8. NAS ≥5 is associated with NASH diagnosis; NAS <3 is inconsistent with NASH. Fibrosis stage is assessed separately (0–4) and is NOT part of the NAS but is the strongest predictor of liver-related mortality.
Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.