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AJCC - American Joint Committee on Cancer prepares the cancer staging forms which are used to determine the treatment and prognosis of each cancer. See stage.

Anaplasia/Anaplastic - This is related to differentiation and refers to cancer cells which have a total lack of differentiation.

Apoptosis - Programmed cell death. It occurs when cells are damaged too much to be restored by normal repair system, therefore cells die typically swell and burst, spilling their contents over their neighbors.

Atypia - A general term describing cells that vary in appearance from the normal cell. This variation may be related to inflammation or may be a cancerous or precancerous condition.

Chondroblast - A chondroblast is a cell which forms cartilage. It arises from the same cell type as bone forming cells called osteoblasts. Chondroblasts may be able to differentiate into osteoblast-like cells.

Collagen - This soft tissue forms the majority of the supporting tissue support for cells, blood vessels, and the framework for organs. It is produced by the fibroblast.

Cytogenetics - A study of genetics which deals with cells.

Cytoplasm - This the portion of the cell within the membrane and outside of the nucleus. In it is housed the majority of energy, enzyme, and protein production.

Desmoplasia, Desmoplastic - As a cancer cell invades the surrounding tissue, the host body's response attempts to keep the cancer cells in check by forming a connective tissue barrier of new collagen. This host response is termed desmoplasia and is a hallmark of invasion and malignancy.

Differentiation - Describes the degree or extent that cancer cells resemble normal cells. Cancer cells that closely resemble the normal cells of the tissue it is derived from are termed well-differentiated (does not spread aggressively); moderately differentiated (is intermediate in aggressiveness or spread). If the cancer cells are primitive appearing or bizarre in appearance, it is termed poorly differentiated or undifferentiated (spreads aggressively).

Dysplasia - Disorderly but non-cancerous growth. It usually refers to changes that occur in epithelium. Although non-cancerous, when advanced, it is considered a significant risk factor for the development of cancer. Squamous dysplasia seen in cervical cancer and pap smears is probably the best known example.

Embryonal - Pertaining to the embryo. Cells are referred to as embryonal if they have retained their ability to divide and have not yet exhibited the differentiated characteristics which distinguish one tissue from another.

Endothelium, Endothelial - These cells form the framework for all blood vessels. The joining together of these cells forms the vessels.

Endoplasmic reticulum - Membrane-bound compartment in the cytoplasm in which lipids and membrane-bound proteins are made.

Epithelium, Epithelial - A specialized lining cell of organs.

Extravasated - Describes blood cell components such as red or white blood cells that have escaped the confines of the blood vessel and are present within the surrounding tissue.

Grade, Grading - One component of prognosis. It is based upon the degree of differentiation of tumor cells. Low grade cancers are well differentiated while high grade cancers are poorly differentiated. Each cancer has a unique grading system and criteria. Many cancers also have a numerical grading system with grade (I) well differentiated cancers to high grade (III-IV) poorly differentiated cancers. In general, low grade cancers behave indolently while high grade cancers behave aggressively.

H and E - Stands for Hematoxylin and Eosin. This is the standard tissue stain which all pathologists and laboratories use. Each tissue will stain with varying combinations of both stains. If the tissue has more of a blue to purple hue, it is termed basophilic, preferentially staining with hematoxylin. If the tissue has a pink to red hue, it is termed eosinophilic, preferentially staining with eosin. A tissue that is neither strongly eosinophilic or basophilic is termed amphophilic.

Hemorrhage - Rupture of blood vessels leading to blood within tissue.

High-grade - A classification of tumors which indicates a high degree of malignancy. The more undifferentiated the cell, the more malignant the tumor.

High Power Field or HPF or hpf - This refers to the highest magnification of a microscope objective. Most pathologists use an objective that magnifies the tissue by a factor of 400x.

Hydropic - Swelling of cells, usually associated with cell injury.

Hyperchromatic - Describes the dark staining of a cell nucleus with routine H and E staining. Usually designates a cell which is actively growing such as a cancer cell.

Immunohistochemistry - A study which involves immunology (study of the immune response), histology (study of the microscopic structure, composition, and function of tissues) and chemistry.

Inflammation - The classic description is redness, heat, pain, swelling, and loss of function. It occurs in every tissue and is present in both cancers and non-cancers. It is a protective response of the body to rid itself of the cause and consequences of cell injury.

Invasion - One of the hallmarks of a malignant tumor describing a growth pattern of cancer cells which have penetrated the basement membrane and have entered the surrounding tissue.

Karyrrhexis - Describes the dissolution and breakdown of a cell nucleus during cell death or necrosis.

Leukocyte - General name for white blood cell or corpuscle.

Li-Fraumeni Syndrome; Li Fraumeni Syndrome - A rare inherited disorder characterized by a high risk of sarcomas of bone and soft tissue, breast cancer, and other tumors.

Low-grade - A classification of tumors which indicates a low degree of malignancy.

Mesenchymal - General term for soft tissues. It includes the collagen connective tissue, neural tissue, smooth and skeletal muscle, and usually cartilage and sometimes bone. Bone cells arise from the mesenchyme.

Mitogen - A substance which leads to transformation of immature cells into cancerous cells.

Mitotic Figure, Abnormal or Atypical Mitotic Figure, Mitotic Rate, Mitotic Index - When a cell divides, it doubles its DNA or genetic material and condenses. Just before the cell divides, this condensed DNA material is visible with routine stains, and this is termed a mitotic figure. A typical mitotic figure is symmetric and well formed. Cancer cells frequently have abnormal quantities of DNA and thus form abnormal or atypical mitotic figures. The mitotic rate and index are related and are a quantitative measure of the number of mitotic figures per a defined area, usually expressed in terms of a microscopic high power field (hpf or HPF). The higher the number of mitotic figures and the mitotic rate or index, the more rapidly a cell is growing, which usually correlates with aggressive growth and poorer prognosis.

Multifocal - Arising independently in several different places.

Mucin - Used to describe a wispy and poorly cellular substance which is present both within the connective tissue and also produced by some gland forming cancers.

Myofibroblast - An atypical fibroblast combining the submicroscopic structural features of a fibroblast and smooth muscle cell; it has a highly irregular nucleus, a large amount of rough endoplasmic reticulum, and a dense collection of filaments of the type which allow muscles to contract.

Necrosis or Necrotic - Cell death.

Neuroblastoma - A type of neuroepithelial tumor which affects mostly infants and children up to 10 years of age; it consists of malignant neuroblasts, usually arising in the autonomic nervous system or in the adrenal medulla.

Nuclear Membrane - This membrane separates the nuclear DNA genetic material from the cytoplasm and the rest of the cell cytoplasm.

Nucleus - The heart of the cell which contains the DNA and genetic material.

Nucleoli - A specialized portion of the nucleus where the DNA material is organized around specialized proteins.

Nucleotide - One of the DNA or RNA bases with the attached sugar and phosphate backbone groups which forms the building block for the DNA or RNA macromolecules.

Oncogene - A gene which when expressed leads to cancer.

Oncoprotein - A protein which is associated with cancer, either because it causes the disease or acts to increase the probability or virulence of a tumor. Oncoproteins are made based on information contained in oncogenes.

p53; p53 protein - A protein product of the p53 tumor suppressor gene, which induces apoptosis when the cell DNA is damaged and cannot be repaired by other repair mechanisms.

p53 negative - A cell or organism with a deletion of the p53 gene or a mutation which causes the p53 gene to be nonfunctional.

p53 positive - A cell or organism with normal or added p53 gene; the product of the gene is detectable.

Pathology - Literally the study (logos) of suffering (pathos).

Perineural Invasion - Describes cancer cells invading in and around nerves. May be an important prognostic factor for some cancers.

Phenotype - The observable characters of a cell or an organism, such as color, shape, appearance etc.

Pleomorphic, Pleomorphism - Variation in size and shape. This usually refers to cancer cell size and shape.

Poorly Differentiated - See differentiated.

Receptor - A molecular structure within or on the surface of a cell characterized by (1) selective binding of a specific substance and (2) a specific physiologic effect that accompanies that binding.

Smooth Muscle - One type of muscle involved in involuntary contraction. Whereas skeletal muscle such as the biceps are voluntary, smooth muscle is usually involuntary, controlled by hormonal and autonomic nervous system. A good example are the muscle layers surrounding the intestinal tract.

Stage, Staging - A measure of cancer prognosis. The four criteria of tumor size, nodal status, grade, and metastasis (TNGM): Size (T) of the primary lesion, (N) spread to regional lymph nodes, (G) the degree of differentiation of tumor cells, (M) and presence or absence of metastases. These four components, taken together, form a TNGM staging system. See the section on staging for more details.

Stroma - General term to describe the connective tissue supporting matrix.

TP53 - The symbol for the p53 gene.

Thrombosis - This is the complex process of blood clot formation within a blood vessel involving injury to the blood vessel, altering the blood flow, and the blood clotting system. If a portion of a thrombus detaches and is carried by the blood to lodge into a distant site, this detached thrombus is called an embolus.

Tumor suppressor gene - A gene that, when normal, exercises control over cell proliferation, usually in conjunction with other genes. When abnormal, a tumor suppressor gene, may fail to properly fulfill its role, with the result that the control of cell proliferation may be damaged to such an extent that the cell becomes cancerous. When all tumor suppressor genes function properly, cell proliferation is fully controlled, with the result that tumors that might otherwise arise in the absence of effective control, are suppressed.

Ultrastructural - Describes morphological changes occuring at the cellular level which usually can only be viewed with an electron microscope.

Undifferentiated - See differentiated.

Vascular Invasion, Lymphatic Invasion - Describes cancer cells invading into and present within the blood or lymphatic vessels. May be an important prognostic factor for some cancers.

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