Neoplasia

Definition and Nomenclature

Literally, neoplasia means new growth and technically, it is defined as abnormal mass of tissues the growth of which exceeds and persists in the same excessive manner after cessation of the stimulus, evoking the transformation. 

Nomenclature:

Neoplasms are named based upon two factors

-   on the histologic types : mesenchymal and epithelial

-   on behavioral patterns : benign and malignant neoplasms

Thus, the suffix -oma denotes a benign neoplasm. Benign mesenchymal neoplasms originating from muscle, bone, fat, blood vessel nerve, fibrous tissue and cartilages are named as Rhabdomyoma, osteoma, lipoma, hemangioma, neuroma, fibroma and chondroma respectively. Benign epithelial neoplasms are classified on the basis of cell of origin for example adenoma is the term for benign epithelial neoplasm that form glandular pattern or on basis of microscopic or macroscopic patterns for example visible finger like or warty projection from epithelial surface are referred to as papillomas. 

This nomenclature has, however, some exceptions

(I)  Nonneoplastic misnomers hematoma, granuloma, hamartoma

(II)  Malgnant misnomers melanoma, lymphoma, seminoma, glioma, hepatoma.

Malignant neoplasm nomenclature essentially follows the same scheme used for benign neoplasm with certain additions. Malignant neoplasms arising from mesenchymal tissues are called sarcomas (Greed sar =fleshy). Thus, it is a fleshy tumour. These neoplasms are named as fibrosarcoma, liposarcoma, osteosarcoma, hemangiosarcoma etc. 

Malignant neoplasms of epithelial cell origin derived from any of the three germ layers are called carcinomas.  Eg. Ectodermal origin: skin (epidermis squamous cell carcinoma, basal cell carcinoma)Mesodermal origin: renal tubules (renal cell carcinoma).Endodermal origin: linings of the gastrointestinal tract (colonic carcinoma) Carcinomas can be fatherly classified those producing glandular microscopic pictures are called Aden carcinomas and those producing recognizable squamous cells are designated as squamous cell carcinoma etc furthermore, when possible the carcinoma can be specified by naming the origin of the tumour such as renal cell adenocarcinoma etc

Tumors that arise from more than tissue components:  

-  Teratomas contain representative of parenchyma cells of more than one germ layer, usually all three layers. They arise from totipotential cells and so are principally encountered in ovary and testis. 

-  Mixed tumors containing both epithelial and mesenchymal components Examples include pleomorphic adenoma and fibroadenoma.

References

Bezabeh ,M. ; Tesfaye,A.; Ergicho, B.; Erke, M.; Mengistu, S.;  Bedane,A. and Desta, A.(2004). General Pathology. Jimma University, Gondar University Haramaya University, Dedub University.