Table 4.
Microscopic features of 146 extracranial meningiomas
| Microscopic characteristic | Extracranial meningiomas |
|---|---|
| Subtype | |
| Meningothelial | 113 (77.4%) |
| Ear and temporal bone (36/38) | 94.7% |
| Nasal cavity and nasopharynx (25/35) | 71.4% |
| Other (soft tissue, neck) (6/14) | 42.9% |
| Skin—scalp (46/59) | 78.0% |
| Atypical | 11 (7.5%) |
| Ear and temporal bone (0/38) | 0 |
| Nasal cavity and nasopharynx (5/35) | 14.3% |
| Other (soft tissue, neck) (4/14) | 28.6% |
| Skin—scalp (2/59) | 3.4% |
| Psammomatous | 6 (4.1%) |
| Ear and temporal bone (2/38) | 5.3% |
| Nasal cavity and nasopharynx (0/35) | 0 |
| Other (soft tissue, neck) (2/14) | 14.3% |
| Skin—scalp (2/59) | 3.4% |
| Anaplastic | 4 (2.7%) |
| Ear and temporal bone (0/38) | 0 |
| Nasal cavity and nasopharynx (0/35) | 0 |
| Other (soft tissue, retroperitoneum) (1/14) | 7.1% |
| Skin—scalp (3/59) | 5.1% |
| Transitional, clear cell, fibrous, metaplastic, angiomatous | 12 (8.3%) |
| Ear and temporal bone (0/38) | 0 |
| Nasal cavity and nasopharynx (5/35) | 14.3% |
| Other (soft tissue, neck) (1/14) | 7.1% |
| Skin—scalp (6/59) | 10.2% |
| Grade | |
| I | 128 (87.7%) |
| Ear and temporal bone (38/38) | 100.0% |
| Nasal cavity and nasopharynx (30/35) | 85.7% |
| Other (soft tissue, neck) (8/14) | 57.1% |
| Skin—scalp (52/59) | 88.1% |
| II (includes atypical and clear cell type) | 14 (9.6%) |
| Ear and temporal bone (0/38) | 0 |
| Nasal cavity and nasopharynx (5/35) | 14.3% |
| Other (soft tissue, neck) (5/14) | 35.7% |
| Skin—scalp (4/59) | 6.8% |
| III (anaplastic) | 4 (2.7%) |
| Ear and temporal bone (0/38) | 0 |
| Nasal cavity and nasopharynx (0/35) | 0 |
| Other (soft tissue, neck) (1/14) | 7.1% |
| Skin—scalp (3/59) | 5.1% |
| Bone invasion present | 31 |
| Psammoma bodies | 45 |
| Pseudoinclusions | 104 |
| Mitotic figures >2/10 HPF | 15 |
HPF high power field