Neuroanatomical classification of pituitary adenomas (based on Hardy, 196932)
| Grade | Size | Location | Bony changes |
|---|---|---|---|
| I | <10 mm | Intrapituitary | None |
| II | >10 mm | Intrasellar or suprasellar expansion, no invasion | Sellar expansion |
| III | Any | Intrasellar or suprasellar expansion, local invasion | Sellar erosion |
| IV | >10 mm | Suprasellar expansion, invasion of extrasellar structures | Bone invasion |