General Veterinary Pathology

Classification

CLASSIFICATION OF NEOPLASM

• Tumours are classified based on histogenesis (Cell of origin) and behavioral pattern (Dangerous to life or not). Based on histogenesis, the neoplasms are classified as simple tumours (Involvement of one cell type), mixed tumours (Involves more than one cell type arising from a single germinal layer) and compound tumours (Cells arising from all germinal layers). Tumours are further classified based on behavioral pattern as benign (not ordinarily fatal) and malignant (usually fatal).

Nomenclature

• The nomenclature of neoplasm has two components: an initial part (Prefix) that indicates the type of cell (Histogenesis) and the following part (Suffix) indicates the benign or malignant nature of neoplasm. All benign tumours have the suffix –oma, while malignant tumours originating from epithelial cells carry the suffix carcinoma and mesenchymal cells carry the suffix sarcoma.

S. No.	Histogenesis	Behaviour
		Benign	Malignant
I.	Simple tumours: Epithelial cells Mesenchymal cells Others	-oma -oma -oma	-carcinoma -sarcoma -oma
I I.	Mixed tumours	Benign mixed tumour	Malignant mixed tumour
I I I.	Compound tumours	Mature teratoma	Immature teratoma

Histological classification of neoplasms

	Benign	Malignant
Epithelial
i. Epidermis	Papilloma	Squamous cell carcinoma
ii. Basal cell (Skin adnexae)	-	Basal cell carcinoma
Adnexae
i. Hair follicle	Trichoepithelioma	Adenocarcinoma
ii. Sebaceous/Sweat/Perianal gland	Adenoma of respective gland	Adenocarcinoma
Non glandular epithelium	Papilloma	Carcinoma
Glandular surface	Polyp	Adenocarcinoma
Glandular epithelium	Adenoma	Adenocarcinoma
Mesenchymal
i. Fibrocyte	Fibroma	Fibrosarcoma
ii. Mucoid connective tissue	Myxoma	Myxosarcoma
iii. Adipose connective tissue	Lipoma	Liposarcoma
iv. Cartilage	Chondroma	Chondrosarcoma
v. Bone	Osteoma	Osteosarcoma
Blood vessel	Angioma or haemangioma	Haemangiosarcoma
Lymph vessel	Lymphangioma	Lymphangiosarcoma
Smooth muscle	Leiomyoma	Leiomyosarcoma
Striated muscle	Rhabdomyoma	Rhabdomyosarcoma
Histiocyte	Histiocytoma	Malignant histiocytoma or histiocytic sarcoma
Mast cell	Mastocytoma	Malignant mast cell tumour or mast cell sarcoma
Haemopoietic tissue
i. Lymphocyte	Lymphocytoma	Lymphosarcoma
ii. Plasma cell	-	Myeloma
iii. Monocyte	-	Monocytic leukemia
iv. Granulocyte	-	Myelogenous leukemia or granulocytic leukemia
v. Reticulum cells	-	Reticulum cell sarcoma
vi. Erythroblasts	-	Erythroid leukemia
vii. Myoloblast	-	Myeloid leukemia
Mesothelium
i. Synovial membrane	Synovioma	Synovial carcinoma
ii. Meninges	Meningioma	Meningioma or invasive meningioma
iii. Bronchial epithelium	-	Bronchogenic carcinoma
Nervous tissue
i. Astrocyte	Astrocytoma	Astrocytoma
ii. Oligodendroglia	Oligodendroglioma	Oligodendroglioma
iii. Ependyma	Ependymoma	Ependymoma
iv. Schwann cells	Schwannoma (neurilemmoma)	Neurilemmoma
v. Nerve cell	Neuroblastoma or Ganglioneuroma	Malignant neuroblastoma or Malignant ganglioneuroma
vi. Chromaffin paraganglia (adrenal medulla)	Pheochromocytoma	Malignant pheochromocytoma
vii. Non chromaffin paraganglia (Carotid body, aortic body)	Chemodectoma or Non chromaffin paraganglioma	Malignant chemodectoma or Non chromaffin paraganglioma or meduloblastoma
Others
i. Neuroectoderm- Melanocyte	Melanoma	Malignant melanoma
ii. Renal epithelium	Renal tubular adenoma	Renal cell carcinoma
iii. Urinary tract epithelium (Transitional)	Transitional cell papilloma	Transitional cell carcinoma
iv. Placental epithelium (Trophoblast)	Hydatidiform mole	Choriocarcinoma
v. Spermatogonic epithelium (Testicular epithelium; germ cells)	Seminoma	Seminoma or Embryonal carcinoma
vi. Kidney	Nephroblastoma	Malignant nephroblastoma
vii. Islet cell	Insulinoma (β cell adenoma)	Malignant insulinoma
viii. Liver ix. Sertoli cell	Hepatoma Sertoli cell tumour	Hepatocellular carcinoma Sertoli cell tumour