The International Medullary Thyroid Carcinoma Grading System (IMTCGS) can be used to grade medullary carcinoma of the thyroid. It is similar to previous grading schemes such as Fuchs et al (current second author). The authors from multiple institutions in the United States, Europe and Australia.
Patient selection: medullary carcinoma of the thyroid
Parameters:
(1) mitotic index (number of mitoses in 2 square mm)
(2) Ki67 proliferative index in precent
(3) tumor necrosis
Two grades: low and high
Criteria for low grade - all of the following:
(1) mitotic index < 5
(2) Ki67 proliferative index < 5%
(3) absence of tumor necrosis
A tumor was high grade any of the following are present:
(1) mitotic index >= 5
(2) Ki67 proliferate index >= 5%
(3) tumor necrosis is present
A patient with a high-grade medullary carcinoma had a worse overall survival with higher risk for adverse findings such as distant metastases.
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