Classification of PPGL based on biochemical and clinical profile
| Biochemical type | Associated PPGL | Lab characteristics | Clinical points |
|---|---|---|---|
| Truly biochemically silent phenotype | Mostly seen in SDHx syndromes | No rise in metanephrines | Mostly associated with head and neck tumors |
| Biochemically pseudo-silent phenotype | Usually happen with very small (less than 5–7 mm) PPGLs | Levels of metanephrines can be normal or near normal, in a misleading way | None |
| Noradrenergic phenotype | Commonly seen in the cluster 1/pseudohypoxia group, including both VHL and SDHx mutations | Elevated normetanephrines | Sustained hypertension and tachycardia are the most common symptoms. Commonly located outside the adrenals |
| Adrenergic phenotype | Commonly seen in the cluster 2/kinase signaling group | Elevated metanephrine or mix of metanephrine/normetanephrine. The latter phenotype can be identified when the plasma free metanephrines are greater than 10% of the sum of metanephrine and normetanephrine | Adrenergic PPGLs are often located in the adrenal gland |
| Dopaminergic phenotype | Commonly seen in SDHx mutations, especially in SDHB | High levels of 3-MT with normal or near-normal levels of metanephrines and normetanephrines | Commonly extra-adrenal and primarily located in the head and neck region |
