Norris grade

Grade 1 was given to neoplasms with some immaturity but with neuroepithelium absent or limited to a rare low-magnification (x40) field within the tumor, and not more than one such focus in any slide.

A grade of 2 was given when immaturity and neuroepithelium were present to a greater degree than grade 1. Neuroepithelium was common but did not exceed three low-power microscopic fields in any one slide.

Grade 3 was given when immaturity and neuroectoderm were prominent, the latter occupying four or more
law-magnification microscopic fields within individual sections.

Grade 0, in which all tissues are mature and mitotic activity is rare or absent, was present only in metastatic deposits, as all well-studied grade 0 primary teratomas are regarded as benign and therefore are excluded from the study.

Reference: Norris HJ, Zirkin HJ, Benson WL. Immature (malignant) teratoma of the ovary: a clinical and pathologic study of 58 cases. Cancer 1976;37:2359-72.

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Cancer 저널은 고맙게도 1976년도 논문이 스캔되어 있어 원문 확인이 용이했다.