Posted by DAM on February 2, 2012 in Disturbance of growth and neoplasia | Short Link
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A tumor or neoplasm is a new growth resulting from an unlimited spontaneous proliferation of cells which occurs without a cause, without control, serving no function and is usually at the expense of the surrounding normal tissues.


The differences between neoplasia and hyperplasia are:

  • In hyperplasia the proliferation of the cells always occurs due to a cause or a stimulus and the hyperplasia stops when the stimulus stops.
  • In neoplasia the growth of the tumor is usually unlimited and it usually does not stop unless the tumor is completely removed or the patient dies.

The tumor is often named by taking the root word of the cells of origin and adding to it “oma” and so we have fibroma, lipoma, and osteoma.

Classification of tumors:

  1. According to the behavior of the tumor are classified into benign or malignant.
  2. According to the tissue of origin, tumors are devided into epithelial tumors, connective tissue tumors, tumors of muscles, tumors of blood vessels … etc.

Difference between benign and malignant tumors




1) rate of growth Slow and limited Rapid and unlimited
2) ways of growth By expansion By infiltration
3) capsule

Usually encapsulated, the capsule is formed by the compressed stroma at the periphery. (Some have no capsule e.g. haemangioma, papilloma, lymphangioma).

Are not usually encapsulated

4) Size Are usually small in size except few as fibromyoma of the uterus and cystadenoma Are usually larger in size
5) ulceration, hemorrhage, necrosis Rare or absent Very common
6) effects Rarely fatal except in C.N.S Usually fatal
7) spread or metastasis Does not spread to distant organs Spread to distant organs
8) recurrence Does not recur after surgical removal recur removal Usually recur
9) Invasion of blood vessels, and lymphatics Absent Present
10) structure a) gross features Smooth surface with fibrotic capsule compress surrounding tissue Irregular surface without capsulation, with destruction of the surrounding tissue.
b) Microscopic features Cells are well differentiated and resemble those of tissue of origin.

Pattern of growth normal and resemble that of parent tissue

Cells do not resemble those of parent tissue i.e.anaplastic and show microscopic criteria of malignancy which are:

–    Pleomorphism.

–    Loss of polarity

–    Hyperchromatic nucleus

–    Nucleus / cytoplasmic ratio is increased.

Nomeneclature of tumors:

Epithelial tumors:

1 .Benign: papilloma (from surface epithelium) or adenoma (from glandular epithelium).

2. Malignant: carcinoma (surface) or adnocarcinoma (glandular).

Mesenchymal tumors:

  1. Benign: are named by adding “oma” at the end e.g. lipoma, myoma, osteoma.
  2. Malignat: are named by adding sacoma at the end e.g. liposarcoma, osteosarcoma..

Comparison of carcinoma and sarcoma




1) Incidence Common Less common
2) Age incidence Commonest in middle and old age Any age but common in young age.
3) Structure a)    Cells arranged in
groups separated by
fibrous stroma.

b)    Hemorrhage and
necrosis are uncommon.

a)    Individual cell
separated from each other
by intercellular substance
(delicate stroma).

b)    Hemorrhage and
necrosis are common.

4) Growth rate Usually slow Usually rapid
5) Metastases or spread. a)    Early lymphatic

b)    Blood-borne
metastases develops late.

c)    Commonest site of
blood-borne metastases is
lung, liver, bone.

a)    lymphatic spread lately.

b)    Blood-borne
metastases develop early.

c)    Commonest site of
metastases is lung

6) Radio sensitivity Radiosensitive Radio resistant
7) Definition Malignant tumor of epithelial tissue Malignant tumor of connective tissue.

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