AFIP Grading System for Mucoepidermoid Carcinoma

The Armed Forces Institute of Pathology (AFIP) scoring system has historically been the most widely accepted scoring system for mucoepidermoid carcinoma.
It is based on 5 histologic features:¹
1. Cystic component < 20% → 2 points
2. Perineural Invasion → 2 points
3. Necrosis → 3 points
4. Mitoses (>= 4 per 10 high power fields) → 3 points
5. Anaplasia → 4 points
Grading is then determined by the total number of points:
- Low Grade: 0-4 points.
- Intermediate Grade: 5-6 points.
- High Grade: >= 7 points.
Mnemonic: PACMAN
- P → Perineural invasion
- A → Anaplasia
- C → Cystic component (< 20%)
- M → Mitotic figures (>= 4/10 hpf)
- A → (AFIP Grading Scheme)
- N → Necrosis.
Brandwein et al. noted considerable grading disparity amongst pathologists and developed a modified grading scheme to improve inter-rater reliabilty,² which is shown below.

Feature	AFIP	Brandwein
Cystic component	(< 20%) 2	(< 25%) 2
Perineural invasion	2	3
Necrosis	3	3
≥4 Mitoses per hpf	3	3
Anaplasia/Nuclear atypia	4	2
Pattern of infiltration (nests/islands)		2
Angiolymphatic invasion		3
Bone invasion		3
Grade	Low Grade: 0-4 Intermediate Grade: 5-6 High Grade: ≥7	Low Grade: 0.1 Intermediate Grade: 2-3 High Grade: ≥4

Auclair, Paul L., Robert K. Goode, and Gary L. Ellis. “Mucoepidermoid carcinoma of intraoral salivary glands evaluation and application of grading criteria in 143 cases.” Cancer 69.8 (1992): 2021-2030. ↩
Brandwein, Margaret S., et al. “Mucoepidermoid carcinoma: a clinicopathologic study of 80 patients with special reference to histological grading.” The American journal of surgical pathology 25.7 (2001): 835-845. ↩

Last updated September 27, 2022