Significance of EGFR/HER2 Expression and PIK3CA Mutations in Giant Cell Tumour of Bone Development

Figure 1

System grading of GCTB. (a) Campanacci grading system. Tumours were classified as the following: grade 1: tumour with well-marginated border of a thin rim of mature bone, and the cortex is intact or slightly thinned but not deformed (picture labelled in yellow). Grade 2: tumour with relatively well-defined margins but no radiopaque rim. The combined cortex and rim of reactive bone is rather thin and moderately expanded but still present (picture labelled in orange). We should note that Grade 2 lesions with a fracture are graded separately. Grade 3: tumour with fuzzy borders, suggesting a rapid and possibly permeative growth. The tumour bulges into the soft tissues, but the soft tissue mass does not follow the contour of the bone and is not limited by an apparent shell of reactive bone (picture labelled in red). (b) GCTB grades based on HE staining. Grade 1: mononuclear cells are few and not atypical with the absence of mitoses. Grade 2: more mononuclear cells with some mitotic figures. Grade 3: predominance of mononuclear cells; giant cells are few with a marked nuclear pleomorphism (HE ×200).

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