Lecture 15 (P) PDF - Tumor Classification and Nomenclature

Nomenclature ◦ Neoplasia means “new growth”: Neo….New, and Plasia…..Growth. ◦ Neoplasm is the collection of cells and stroma composing new growths. ◦ In the modern era, a neoplasm is defined as a genetic disorder of cell growth that is triggered by acquired or less commonly inherited mutation...

Nomenclature ◦ Neoplasia means “new growth”: Neo….New, and Plasia…..Growth. ◦ Neoplasm is the collection of cells and stroma composing new growths. ◦ In the modern era, a neoplasm is defined as a genetic disorder of cell growth that is triggered by acquired or less commonly inherited mutations affecting a single cell and its clonal progeny. ◦ Tumor originally described swelling caused by inflammation, but is now equated with neoplasm. ◦ Oncology (Greek oncos = tumor) is the study of tumors or neoplasms. Terminology Tumor is simply swelling: -Inflammation -Neoplasm Cancer (Latin word for crab): because the finger-like spreading projections from a cancer called to mind the shape of a crab. Neoplasm “… is an abnormal mass of tissue, the growth of which exceeds and is uncoordinated with that of normal tissues and persists in the same excessive manner after cessation of the stimuli which invokes the change. ” Tumor cells’ growth is autonomous i.e. independent of physiologic growth stimuli.  umor Neoplastic Non-neoplastic Monoclonal Polyclonal Hyperplasia Benign Metaplasia Dysplasia Malignant  Tumors-related Non-Neoplastic lesions Hamartoma: present as disorganized but benign-appearing masses composed of cells indigenous to the particular site. Choristoma: a congenital anomaly better described as a heterotopic nest of cells ◦ Mature normal well-developed tissue at abnormal site, such as Pancreatic tissue localized to submucosa of the stomach.  DYSPLASIA Literally means disordered growth. Reversible replacement of one mature (DIFFERENTIATED) cell type by Undifferentiated/ immature (cells of abnormal sizes and shapes) Characteristic features of dysplasia: Often occurs in metaplastic epithelium Disordered but non-neoplastic proliferation Loss of uniformity Pleomorphic and hyperchromatic nuclei Mitoses more abundant than usual No invasion of basement membrane. If dysplasia is marked & involves entire thickness of epithelium, it is considered as carcinoma in situ (pre-invasive stage of cancer) Dysplasia: Dysplasia can be precancerous but does not necessarily progress to cancer. Changes that do not involve entire thickness of epithelium may be reversible, if the cause is removed the epithelium may revert to normal.  Cancer Dysplasia Growth factors Chronic Irritant  Classification of Neoplasms ◦ Based on clinical and biological behaviour:  Two main groups are recognized: 1. Benign. 2. Malignant.  Two broad categories of neoplasms on basis of pattern of growth Neoplasms Benign Malignant Microscopic & macroscopic Referred to as Cancer, can characteristics are innocent, invade & destroy adjacent amenable to surgical removal tissues & spread to distant sites. 1. Encapsulated 1. Un-encapsulated 2. Slow-growing 2. Fast-growing 3. Non-invasive 3. Invasive 4. Remain localized 4. Metastasize 5. Well-differentiated 5. Well, moderate, and poorly- differentiated/ anaplastic  Tumor structure All tumors, benign and malignant, have two basic components: 1. Parenchyma: ◦ Made up of clonal/transformed neoplastic cells ◦ Resembles normal tissue (well- differentiated) in benign tumors ◦ In malignant neoplasms, neoplastic cells could be well differentiated, moderately differentiated or poorly differentiated or pleomorphic (anaplastic) 2. Reactive stroma (Non-Neoplastic supporting tissues): ◦ Made up of connective tissue, blood vessels, and variable numbers of macrophages and lymphocytes. ◦ Important for growth and evolution of neoplasms. “Tumor nomenclature is based on parenchymal component” Classification of Tumors based on cell of origin 1. Composed of one parenchymal cell type: ◦ Tumors of mesenchymal origin ◦ Tumors derived from endothelial and related tissues ◦ Tumors of epithelial origin ◦ Tumors of melanocytes 2. Composed of more than one neoplastic cell type, derived from one germ cell layer ◦ Mixed tumors of salivary glands 3. Tumors composed of more than one neoplastic cell type, derived from more than one germ cell layer- ◦ Teratoma Neoplasm ◦ Tumours can arise from any cell ◦ Mesoderm ◦ Ectoderm ◦ Endoderm ◦ Benign ◦ Malignant  Nomenclature Neoplasm Ectoderm Endoderm Benign Mesoderm Malignant Carcinoma Sarcoma Haemopoietic / lymphoid neoplasms Melanoma Germ cell tumors  Nomenclature Neoplasm Benign Malignant adenoma angioma Rhabdomyoma lipoma Carcinoma Sarcoma chondroma Osteoma leiomyoma  Nomenclature Neoplasm Benign Malignant Mesenchymal tissue Carcinoma Sarcoma Fibrosarcoma Chondrosarcoma leiomyosarcoma  Nomenclature Neoplasm Benign Malignant Epithelial origin Carcinoma Sarcoma squamous cell carcinoma adenocarcinoma, Renal cell carcinoma  Nomenclature Benign Tumors ◦ The suffix “oma” is added to the cell type from which the tumor arises BENIGN MESENCHYMAL TUMOURS Fibroma Chondroma Leiomyoma & rhabdomyoma Epithelial Tumors Epithelium is derived from all three germ-cell layers ◦ Ectoderm – skin ◦ Endoderm – lining epithelium of GIT ◦ Mesoderm – renal tubular epithelium So Mesoderm may give rise to carcinoma (epithelium) and sarcoma (mesenchymal) Nomenclature Benign epithelial tumors Adenoma Papilloma Polyp Cystadenoma/ Papillary cystadenoma Nomenclature of Malignant Tumors ◦ Malignant neoplasms of epithelial cell origin are called carcinomas ◦ Stratified squamous epithelium: squamous cell carcinoma ◦ Glandular pattern: Adenocarcinoma ◦ Placental epithelium: Choriocarcinoma ◦ Basal cells of skin : Basal cell carcinoma ◦ Urinary epithelium : Urothelial carcinoma (transitional cell carcinoma) ◦ Unknown tissue origin: Poorly diff. malignant tumor  Nomenclature of Malignant Tumors ◦ Malignant tumors arising from mesenchymal tissue are called sarcomas ◦ Fibrous tissue: fibrosarcoma ◦ Cartilage: chondrosarcoma ◦ Blood vessels: angiosarcoma ◦ Muscles: leiomyosarcoma & rhabdomyosarcoma Tumors Derived from One Germ Cell Layer; Mixed tumors of salivary glands ◦ Neoplastic cells are monoclonal but in some cases can show divergent differentiation, creating mixed tumors in which both epithelial & mesenchymal components(fibrous tissue, bones & cartilage) are seen. Nomenclature ◦ Tumors cells differentiating along more than one cell lineage, but derived from one germ layer - MIXED TUMOURS ◦ Benign : ◦ Pleomorphic adenoma of salivary glands ◦ Fibroadenoma of breast ◦ Malignant: ◦ Malignant mixed tumor of salivary glands ◦ Phylloides tumor of the breast ◦ Wilms tumor of kidney Nomenclature ◦ Tumors comprising of more than one neoplastic cell type, derived from more than one germ layer –Teratogenous ◦ TERATOMA ◦ Composed of multiple tissues foreign to the site of growth (bone, muscle, hair, skin, brain) ◦ Arises in the gonads (testis or ovary) or in the midline of the body ◦ Benign: Mature teratoma (dermoid cyst) ◦ Malignant: Immature teratoma Tumors Derived from More than One Germ Cell Layer Teratoma of Ovary  Neoplasia Nomenclature (“… -oma’s” any growth ) examples : benign - malignant Benign tumor Malignant tumor Squamous cell Squamous epithelium Papilloma carcinoma Glandular epithelium Adenoma Adenocarcinoma Fat Lipoma Liposarcoma Bone Osteoma Osteosarcoma Skeletal Muscle Rhabdomyoma Rhabdomyosarcoma Characteristics of Benign versus Malignant Tumors Four fundamental rules by which benign tumors can be distinguished from malignant tumors: 1. Differentiation & anaplasia 2. Rate of growth 3. Local invasion 4. Metastasis  Rules to differentiate benign from malignant tumors 1-Differentiation & Anaplasia ◦ Differentiation refers to the extent to which neoplastic parenchymal cells resemble the corresponding normal parenchymal cells, both morphologically & functionally. ◦ Differentiation and anaplasia refers only to the parenchymal cells (i.e. tumor cells) ◦ Correlation with biologic behavior ◦ Benign tumors are well differentiated ◦ Malignant tumors can range from well to undifferentiated. ◦ Undifferentiated malignant tumors have no functional activity and worse prognosis Classification of tumor based on degree of Differentiation Well differentiated neoplasm ◦ Tumor cells resembles mature cells of tissue of origin ◦ Scanty mitoses Moderately well differentiated neoplasm ◦ In-between the two extremes of well-diff. vs. un-diff. tumors Undifferentiated or anaplastic tumor: ◦ Malignant neoplasms that are composed of poorly differentiated cells are said to be anaplastic. Anaplasia Malignant neoplasm composed of undifferentiated cells are said to be anaplastic Anaplasia means loss of functional & structural differentiation Marked pleomorphism (variation in size & shape of cells) Large & hyperchromatic nuclei High nuclear to cytoplasmic ratio Brisk mitoses Giant cells Loss of organization Anaplasia is the hallmark of malignancy Abnormal mitosis in an anaplastic cell