Neoplasia lecture

Oncology

• The term oncology literally means a branch of science that deals with tumours and cancers. The word “onco” means bulk, mass, or tumor while “-logy” means study.

• Neoplasm (from ancient Greek neo-, "new" + plasma, "formation", "creation") or tumor is an abnormal mass of tissue as a result of abnormal growth or division of cells.

Classification of NeoplasmsTissue Origin Benign Malignant Examples

Epithelial

Glandular Adenoma Adenocarcinoma Thyroid follicular adenomaAdenocarcinoma of lung

Squamous and Transitional

Polyp, papilloma

Squamous cell carcinomaTransitional cell carcinoma

Squamous papiloma of skinSquam. cell carcinoma skin

Connective tissue Tissue type + suffix (-oma)

Sarcoma Osteoma, Osteosarcoma, Hemangioma, Hemangiosarcoma

Hematopoietic & lymphoreticular

LymphomaLeukemia

Large cell lymphomaHodgkin’s diseaseMylocytic leukemia

Neural tissue NeuromaNeurofibroma

SarcomaBlastoma

Glioblastoma multiformeNeurofibrosarcoma

Mixed tissues of origin

Teratoma Teratocarcinoma Teratoma of ovaryTeratocarcinoma of testis

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Histogenetic classification of benign tumors

Normal tissue Resultant Benign tumorGlandular epitheliumSurface epitheliumFibroblastsCartilageStriated MuscleSmooth MuscleBlood VesselsFatBoneLiver

AdenomaPapillomaFibromaChondromaRhabdomyomaLeiomyomaHemangiomaLipomaOsteomaHepatoma

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Histogenetic classification of malignant tumorsNormal tissue Resultant Malignant tumorEpitheliumConnective tissueBone Marrow

CarcinomaSarcomaLeukemia

More Specifically:Glandular epitheliumSquamous epitheliumFibroblastsCartilageStriated MuscleSmooth MuscleEndotheliumFatBoneLiver

AdenocarcinomaSquamous carcinomaFibrosarcomaChondrosarcomaRhabdomyosarcomaLeiomyosarcomaAngiosarcomaLiposarcomaOsteosarcomaHepatocellular carcinoma

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Sarcoma/carcinoma

• A sarcoma is a cancer that arises from transformed cells of mesenchymal origin. Thus, malignant tumors made of cancerous bone, cartilage, fat, muscle, vascular, or hematopoietic tissues are, by definition, considered sarcomas.

• Malignant tumor originating from epithelial cells, which are termed carcinoma. Common malignancies, such as breast, colon, and lung cancer, are almost always carcinoma.

Charateristics of neoplastic cells Abnormal size and irregular shape of cells. Nuclei Nuclei increase in size Nucleolus (a) often prominent (b) sometimes multiple (c)

Atypical staining Numerous mitotic figures May be multiple----------tumour giant cells Varying amount of cytoplasm (a) generally cytoplasm

decrease in amount (b) fibrillar appearance with few secretory granules (c) basophilic in nature

Cytoplasm to nucleus ratio is lost disturbed polarity of cells

Microscopic structure of tomour Parenchyma; cells make up of the tumour Cells of abnormal structure deviation from normal is least in benign, somewhat resemble normal

tissue and marked in malignant arrangement of tumour cells1. Epithelial tumours (a) sheets or fronds in superficial epithelium (b)

clumps,columns or acini within a tumour mass (c) Each cell fastened directly to the next.

2. Connective tissue tumours (a) Tumour cells lie singly,may arrange in whorls or bundles (b) Each cell is separated from the next by the intercellular substances

3. Hemopoitic tumours (a) tumour cells form (b) neoplastic cells closely packed but remain discrete.

Microscopic structure of tomour Stroma;Support and nourishes the tumour cells Amount is variable least in histoid tumours(A type of connective tumor that is

composed of a single type of differentiated tissue) Reasonable in organoid tumours(A tumor that is glandular

in origin and that contains epithelium, connective tissue, and other tissue structures that give it a complex structure similar to an organ)

May be compact or edematous Blood vessels vary in appearance Tumour cells do not require innervation

Benign tumor

Capsule

Smooth muscles

Here is an osteosarcoma of bone. The large, bulky mass arises in the cortex of the bone and extends outward

This is an example of metastases to the liver, tan-white masses are multiple and irregularly sized.

Mitotic figures

What is the significance of mitotic figures in a neoplasm?

• In general, their appearance suggests a higher rate of cellular proliferation. Mitoses certainly are present in normal tissues (surface epithelia are constantly regenerating, and hematopoiesis produces billions of new blood cells each day). However, the presence of mitoses, and particularly abnormal mitoses, in a mass lesion supports a diagnosis of neoplasia, and likely a malignant neoplasm.

• Hepatocellular carcinoma cells. Characterized by large anaplastic carcinoma cells with eosinophilic cytoplasm, large hyperchromatic nuclei and prominent nucleoli. The normal trabecular structure of the liver is distorted.