Neoplasia/Tumour

Definition: (Neoplasia/Tumour): A tumour is an abnormal mass of tissue, the growth of which exceeds and is uncoordinated with that of the normal tissue and persists in the same excessive manner after cessation of the stimuli which evoked the change. (Ref-Robbins/7^th/270; Walter & Israel/7^th/425)

Types/Classification:

Basis of tu mour classification: The following bases for classification of tumour may be recognized-

1.     Naked eye appearance including the organ of origin.

2.     Histogenetic (Including embrylogical considerations)

3.     Histological.

4.     Behavioural.

5.     Aetiological.

6.     Functional.

Behavioral classification:

1.     Benign tumour (e.g.- squamous cell papilloma)

2.     Malignant tumour (e.g – squamous cell carcinoma)

a)     Primary:

·        Carcinoma

·        Sarcoma

b)    Secondary

Difference between benign and malignant tumors:

Tissue of origin	Benign tumour	Malignant tumour
1.     Startified squamous	Squamous cell papilloma.	Squamous cell or epidermoid carcinoma.
2.     Basal cells of skin or adnexa	-	Basal cell carcinoma.
3.     Epithelial lining of glands or ducts	Adenoma Papilloma Cystadenoma	Adenocarcinoma Papillary carcinomas Cystadenocarcinoma
4.     Respiratory passages	Bronchial adenoma	Bronchogenic carcinoma
5.     Renal epithelium	Renal tubular adenoma	Renal cell carcinoma
6.     Liver cells	Liver cell adenoma	Hepatocellular carcinoma
7.     Urinary tract epithelium (Transitional)	Transitional cell papillma	Transitional cell carcinoma
8.     Placental epithelium	Hydatidiform mole	Choricarcinoma
9.     Testicular epithelium (germ-cells)	-	Seminoma Embryonal carcinoma