Tumor Grade Vs. Stage Grade histologic assessment of how closely a neoplasm resembles the original tissue graded I-IV score given on degree of differentiation and number of mitoses important determinant of prognosis the less a tumor resembles the original tissue the worse the prognosis Stage degree of size and spread of a neoplasm typically has more prognostic value than grade importance in determining stage metastasis (non-lymph node) > lymph node involvement > size of tumor TNM staging system is commonly used to describe the stage T = size of tumor N = node involvement M = metastases determined after surgical resection of tumor Tumor nomenclature Carcinoma denotes epithelial origin Sarcoma denotes mesenchymal origin Tumor nomenclature Cell type Benign Malignant Epithelium Adenoma, papilloma Adenocarcinoma and papillary carcinoma Melanocyte Nevus Melanoma Mesenchyme Blood cells n/a Leukemia and lymphoma Blood vessels Hemangioma Angiosarcoma Smooth muscle Leiomyoma Leiomyosarcoma Skeletal muscle Rhabdomyoma Rhabdomyosarcoma Bone Osteoma Osteosarcoma Fat Lipoma Liposarcoma >1 cell type Mature teratoma (women) Immature teratoma and mature teratoma (men) Tumor differences Benign usually well-differentiated (i.e. low grade) slow growing well circumscribed no metastasis Malignant may be poorly differentiated (i.e. high grade) erratic growth poorly circumscribed may metastasize