Ho et al developed criteria for classifying an ependymoma as anaplastic. This correlates with survival. The authors are from the Veterans General Hospital in Taipei, Taiwan.
Parameters:
(1) mitotic rate in 10 consecutive high power fields
(2) hypercellularity
(3) proliferation of endothelium
(4) tumor necrosis
Parameter
Finding
Points
mitotic rate
< 4 per 10 high power fields
0
>= 4 per 10 high power fields
1
hypercellularity
absent
0
present
1
endothelial proliferation
absent
0
present
1
tumor necrosis
absent
0
present
1
where:
• The microscopic field area using the high power lens is given as 0.24 square mm. 10 hpf would be an area of 2.4 square mm. A mitotic rate of 4 in 10 high power fields correlates to 1.67 mitoses per square mm.
total score =
= SUM(points for all 4 parameters)
Interpretation:
• minimum score: 0
• maximum score: 4
• A score >= 2 indicates an anaplastic ependymoma.
• A score >= 2 and subtotal resection was associated with increased risk of recurrence.
Score
10 Year Survival
0 or 1
90%
2 - 4
56%
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