Topics: Cancer, Cell cycle, Oncology Pages: 34 (10520 words) Published: April 25, 2011
Presented by Dr Abudu Emmanuel Kunle (MBBS, M.Sc, FMCPath) Senior Lecturer and Consultant Histopathologist University of Uyo Teaching Hospital,Uyo, Akwa- Ibom State, Nigeria.

Neoplasia means the process of new growth whilst Neoplasm means a new growth. Sometimes, the parenchyma cells stimulate the formation of an abundant collagenous stroma, referred to as desmoplasia. Some tumours e.g. some cancers of breast are stony hard or scirrhous. Sarcomas have little connective tissue stroma and so are fleshy. Pseudo tumours: i) An ectopic rest of normal tissue is sometimes called a choristoma e.g a rest of adrenal cells under the kidney capsule or a pancreatic nodular rest in the mucosa of the small intestine may mimic neoplasm.


Ii) Hamartoma = a mass of disorganized but mature specialized cells or tissue indigenous to the particular site e.g. a hamartoma in the lung may contain islands of cartilage, blood vessels, bronchial-type structures, & lymphoid tissue and sometimes, the lesion is purely cartilaginous or purely angiomatous. A true tumour could be benign or malignant This is subclassified into epithelial or mesenchymal in origin. Other types: lymphoma, melanoma Epithelial: non glandular (squamous, transitional,papilloma Glandular(adenoma/ adenocarcinoma Seminoma tends to spread to lymph node along the iliac artery and aorta and highly radiosensitive i.e. responds well to radiotherapy. Embryonic carcinoma of the testis is not radiosensitive and tends invade locally beyond the confines of the testis and spread throughout the body

a) Biology of tumour growth: Benign and malignant neoplasms

The nature history of most malignant tumours can be divided into 4 phases: 1) malignant change in the target cell (transformation); 2) growth of the transformed cells; 3) local invasion; and 4) distant metastases. Differentiation refers to the extent to which neoplastic cells resemble comparable normal cells, both morphologically and functionally.

a) Biology of tumour growth: Benign and malignant neoplasms contd

1) Anaplasia is marked by: 1) pleomorphism; 2) abnormal nuclear morphology; 3) mitoses which atypical, bizarre, sometimes tripolar, quadripolar or multipolar spindles; 4) loss of polarity; 5) tumour giant cells characterized by hyperchromatic nuclei and large in relation to the cell (differential diagnosis= Langhans or Foreign body giant cells which contain small, normal-appearing nuclei); and 6) necrosis because they outgrow their scanty stromal vascular supply.

a) Biology of tumour growth: Benign and malignant neoplasms contd

Dysplasia means disordered growth especially seen in epithelia and characterized by: 1) loss in the uniformity of the individual cells; 2) loss in their architectural orientation i.e. the usual progressive maturation of tall cells in the basal layer to flattened squames on the surface may be lost and replaced by a scrambling of dark basal-appearing cells throughout the epithelia; 3) pleomorphism; 4) hyperchromatic nuclei; 5)mitotic figures are more abundant than usual, but conform to normal patterns and appear in abnormal location within the epithelia, i.e. mitoses are not confined to the basal layers and may appear at all levels and even in surface cells.

a) Biology of tumour growth: Benign and malignant neoplasms contd

2) Rate of growth: is determined by 3 main factors namely: i) the doubling time of tumour cells, ii) the fraction of tumour cells that are in the replicative pool, and Iii) the rate at which cells are shed and lost in the growing lesion. As tumour continues to grow, cells leave the proliferative pool in ever-increasing numbers owing to shedding, lack of nutrients, apoptosis; by differentiating; and by reversion to Go or G1 phases and thus debulking (Surgery) is done to shift the tumour cells into cell cycle, thus now responding to chemotherapy or radiotherapy esp cancer of colon and breast....
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