Parameters from multivariate analysis:
(1) extent of resection based on the Simpson Grade
(2) histologic type
(3) CT scan appearance after enhancement
(4) number of mitoses in 10 high power microscopic fields (x400)
In Table 7 the relative risk for each factor was from 2.1 to 2.3. Table 6 and Figure 4 show the effect of Simpson grades on risk. This data can be used to construct a risk score (not included in the article).
|
Parameter
|
Finding
|
Points
|
|
Simpson grade
|
I
|
0
|
|
|
II
|
1
|
|
|
III to V
|
2
|
|
histologic grade
|
conventional
|
0
|
|
|
unconventional (atypical or malignant)
|
1
|
|
CT scan
|
homogeneous
|
0
|
|
|
heterogeneous
|
1
|
|
mitoses per 10 hpf
|
0 to 2
|
0
|
|
|
>= 3
|
1
|
where:
• Heterogeneous CT appearance may be due to necrosis in the tumor.
• CT signs of an unconventional meningioma include irregular margin and peritumoral edema (page 929).
• The number of mitoses would be affected by the area for the microscopic field.
total risk score =
= SUM(points for all 4 parameters)
Interpretation:
• minimum score: 0
• maximum score: 5
• A meningioma that is low risk for recurrence has no risk factors (score = 0). These showed a recurrence rate of 4% at 5 years and 18% at 10 years).
• The authors describe intermediate and high risk groups on page 927. Based on the description a score of 1 would indicate intermediate risk while 2 or greater high risk.
