GAPP Grade (Pheochromocytoma and Paraganglioma)
GAPP, the Grading system for Adrenal Pheochromocytoma and Paraganglioma (Kimura and colleagues, Endocr Relat Cancer 2014), which grades the metastatic potential of a resected specimen from 0 to 10.
Open the calculator → Runs in your browser. Data leaves only if you deliberately send a problem report from the interactive tool.
Example
- Histological pattern: Large and irregular cell nest
- Yes
- Histological pattern: Pseudorosette, even if focal
- No
- Comedo-type necrosis
- Yes
- Cellularity
- Moderate, 150 to 250 cells per unit area
- Ki-67 labelling index band
- 1 to 3 percent
- Vascular or capsular invasion
- No
- Catecholamine type
- Noradrenergic: raised urine normetanephrine without raised metanephrine
Result: GAPP 6 of 10
The tool opens with these values already filled in. Replace them with your own.
What the result means
- Pattern
- Zellballen 0; irregular cell nest 1; pseudorosette 1. THESE ADD - both present scores 2.
- Why additive
- A single pattern point caps the total at 9, but the published maximum is 10. Only additivity reaches it.
- Necrosis
- Comedo-type necrosis, 2 points if present.
- Cellularity
- Low <150 = 0; moderate 150-250 = 1; high >250 cells per unit area = 2. Operator-dependent.
- Ki-67
- Under 1% = 0; 1-3% = 1; over 3% = 2.
- Invasion
- Vascular or capsular invasion, 1 point.
- Catecholamine
- Non-functioning 0, adrenergic 0, noradrenergic 1. NON-MONOTONIC, and from urine not the slide.
- WD 0-2
- Well differentiated. ~100% five-year survival reported.
- MD 3-6
- Moderately differentiated. ~67%.
- PD 7-10
- Poorly differentiated. ~22%.
- Scope
- NO grade excludes metastasis. Not a reason to stop surveillance. SDHB is not part of GAPP.
What you enter
- Histological pattern: Large and irregular cell nest.
- Histological pattern: Pseudorosette, even if focal.
- Comedo-type necrosis.
- Cellularity, counted in cells per unit area at a specified magnification and therefore operator-dependent
- Ki-67 labelling index band
- Vascular or capsular invasion.
- Catecholamine type, a BIOCHEMICAL variable from 24-hour urine fractionated metanephrine and normetanephrine, NOT from the slide.
Full field descriptions
- Histological pattern: Large and irregular cell nest. 1 point. ADDS with the other pattern feature - they are NOT alternatives, and a tumor showing both scores 2.
- Histological pattern: Pseudorosette, even if focal. 1 point. ADDS with the other pattern feature - they are NOT alternatives, and a tumor showing both scores 2.
- Comedo-type necrosis. 2 points if present.
- Cellularity, counted in cells per unit area at a specified magnification and therefore operator-dependent [low = Low, under 150 cells per unit area, 0 points; moderate = Moderate, 150 to 250 cells per unit area, 1 points; high = High, over 250 cells per unit area, 2 points]
- Ki-67 labelling index band [under-1 = Under 1 percent, 0 points; 1-to-3 = 1 to 3 percent, 1 points; over-3 = Over 3 percent, 2 points]
- Vascular or capsular invasion. 1 point if present.
- Catecholamine type, a BIOCHEMICAL variable from 24-hour urine fractionated metanephrine and normetanephrine, NOT from the slide. NON-MONOTONIC: non-functioning scores the same as adrenergic and LESS than noradrenergic [non-functioning = Non-functioning, 0 points; adrenergic = Adrenergic: raised urine metanephrine, with or without raised normetanephrine, 0 points; noradrenergic = Noradrenergic: raised urine normetanephrine without raised metanephrine, 1 points]
How this is calculated
Kimura N, Takayanagi R, Takizawa N, et al. Pathological grading for predicting metastasis in phaeochromocytoma and paraganglioma. Endocr Relat Cancer. 2014;21(3):405-414. Read the source ↗
A reference and educational tool. Not medical, legal, or financial advice, and not a substitute for clinician judgment.