Neoplasia Dr. Raid Jastania
Neoplasia: Terminology • Cancer is the 2nd cause of death in the US • Neoplasia is “new growth” • Neoplasm is an abnormal mass of tissue the growth of which exceeds and is uncoordinated with that of the normal tissues and persists after cessation of stimuli (By Willis)
Neoplasia: Terminology • Loss of normal growth (growth autonomy) • Loss of normal differentiation • Transformation • Tumor: swelling, mass of tissue • Oncology: Study of tumors • Benign vs Malignant • Benign: localized, not fatal • Malignant: cancer, invasive, metastasize, fatal
Neoplasia: concept of origin • Zygote – cells – tissues – organs – human • DNA, genetic material, genes are the present in all the cells of the body • Cells differ in gene expression • Type of cells (based on genes expressed) • Control of growth • Differentiation • Monoclonality is the basis of neoplasia • Tumor progression, divergent differentiation
Nomenclature • Benign tumors • Suffix “–oma” is added to the cell type • Fibrous: fibroma • Cartilage: chondroma • Bone: osteoma • Adipose tissue: lipoma • Smooth muscle: leiomyoma • Skeletal muscle: rhabdomyoma • Blood vessels: hemangioma • Epithelial: adenoma (cystadenoma, papilloma)
Nomenclature • Malignant tumors • Mesenchymal: sarcoma • Fibrous: fibrosarcoma • Cartilage: chondrosarcoma • Bone: osteosarcoma • Adipose: liposarcoma • Smooth muscle: leiomyosarcoma • Skeletal muscle: rhabdomyosarcoma • Blood vessels: angiosarcoma • Epithelial: carcinoma • Gland forming: adenocarcinoma • Squamous: Squamous cell carcinoma • Transitional cell: Transitional cell carcinoma (urothelial carcinoma)
Nomenclature • Mixed tumors: • Pleomorphic adenoma of salivary gland • Fibroadenoma of breast • Teratoma: more than one germ-cell layer • Teratoma contains: bone, epithelium, muscle, fat, nerve….
Nomenclature • Exceptions: • Malignant tumors • Lymphoma, melanoma, mesothelioma, seminoma • Hamartoma: not neoplastic, it is rather a malformation. Hamartoma contain mixture of mature (adult-type) tissue in abnormal distribution and arrangement • Choristoma: Hetrotopic rest. It is normal tissue in abnormal place.
Benign and Malignant • How do we know benign from malignant tumor? • Features: • Differentiation and Anaplasia • Rate of Growth • Local Invasion • Metastasis
Differentiation and Anaplasia • Differentiation is the extent to which tumor cells resemble their normal cells morphologically and functionally • Generally: • Benign tumors are well differntiated • Malignant tumors can be well differentiated, moderately differentiated or poorly differentiated. They can be “undifferentiated” • Anaplasia is lack of differentiation
Differentiation and Anaplasia • Anaplasia is lack of differentiation • Peomorphism • Hyperchromatic nuclei • High nuclear to cytoplsmic ratio (N/C ratio) • Giant cells • Mitosis • Loss of polarity and normal arrangement • Loss of sturcture
Differentiation and Anaplasia • Function: • Benign tumors: have normal function eg. Adrenal cortical adenoma • Malignant tumors: have variable function according to the degree of differentiation eg. Hepatocellular carcinoma produces bile
Differentiation and Anaplasia • Dysplasia: • Not neoplstic growth • Disordered growth and differentiation • Show mild anaplastic features eg. Nuclear pleomophism, hyperchromasia, mitosis….
Rate of Growth • Benign: slow growing • Malignant: fast growing
Relation between Growth and Differentiation
Local Invasion • Benign tumors: localized, may be surrounded by pseudocapsule “capsule” • Malignant: invasive, infiltrating, destructiv, penetrating
Metastasis • Secondary implants discontinuous from the primary tumor • 30% of newly diagnosed cancer has metastasis • 20% has occult metastasis • Modes of metastasis: • 1. Seeding in body cavity • 2. Lymphtics: lymph nodes • 3. Hematogenous: liver, lung, brain….
Benign and Malignant • In summary, Features of malignancy are • Less Differentiation and More Anaplasia • Rate of Growth - high • Local Invasion • Metastasis
