| L |
LG: Low grade: round monomorphic nuclei with only mild to moderate nuclear size variation, indistinct nucleoli, and chromatin characteristics resembling those of normal parathyroid or of adenoma |
| H |
HG: High grade: more pleomorphism, with a nuclear size variation greater than 4:1; prominent nuclear membrane irregularities; chromatin alterations, including hyperchromasia or margination of chromatin; and prominent nucleoli. High-grade tumors show several discrete confluent areas with nuclear changes |
| A |
Well differentiated |
| B |
Moderately differentiated |
| C |
Poorly differentiated |
| D |
Undifferentiated, anaplastic |
| 9 |
Grade cannot be assessed (GX); Unknown |
