Neoplasia

TYPES OF TUMOURS

There are two main types:

>benign tumours

>malignant tumours

BENIGN TUMOURS

The names of these tumours and with -oma

Eg: adenomas-benign epithelial tumors arising in glands forming glandular patterns

MALIGNANT TUMOURS

These are also called cancers and are divided into two general categories:

>carcinomas-arising from epithelial tissue

>sarcomas-arising from mesenchymal tissue

Eg adenocarcinoma-malignant growth tumours forming glandular patterns

NB: some tumors arise from more than one parencymal cell type

>mixed tumours-from one germ layer that diffrentiates into more than one parenchymal cell type.

>teratomas-made up from parenchymal cells from more than one germ layer.

TUMOURS ARE CLASSIFIED BASED ON

a>DIFFRENTIATION

b>RATE OF GROWTH

c>LOCAL INVASION

d>METASTASES

a>Diffrentiation-is the extent to which tumor cells resemble comparable normal tissue.

Anaplasia-this is lack of diffrentiation whereby there is

*nuclear and cellular pleomorphism

*hyperchromasia

*increased nuclear-cytoplasmic ratio

*abundant mitoses

*loss of polarity

*tumor giant cells

b>Rate of growth-is the rate at which the tumour grows.

c>Local invasion-is whether the tumor invades the surrounding normal tissue or is confined within its capsule.

d>metastases-is the ability of whether the tumour can spread to distant sites and th routes by which this can occur are

1.spread into body cavities

2.invasion of lymphatics.

3.hematogenous spread-via the blood circulation.this is typical of all sarcomas and a few carcinomas

a>diffrentiation

*benign-are normally well diffrentiated and normally resemble the surrounding normal tissue

*malignant-range from well diffrentiated to poorly diffrentiated cells and there may also be a total lack of diffrentiation (anaplasia)

b>Rate of growth:

*benign-is normally slow and may take years to develope

*malignant-the rate is normally rapid

c>Local invasion:

*benign-does not invade the surrounding nornal tissue and the tumors are mostly encapsulated.

*malignant-are invasive and infiltrative and destroy the surrounding normal tissue.

d>Metastases:

*benign-does not metastasize.

*malignant-metastases is the hallmark for malignant tumours.