Important Definitions in Oral Pathology

A neoplasm, as defined by Willis, is 'an abnormal mass of tissue the growth of which exceeds and is uncoordinated with that of the normal tissues and persists in the same excessive manner after the cessation of the stimuli which evoked the change.'

Premalignant / Precancerous lesion
A morphologically altered tissue in which cancer is more likely to occur than in its apparently normal counterpart.  - WHO 1973

Premalignant / Precancerous condition
A generalized state associated with a significantly increased risk of cancer. - WHO 1973

Potentially malignant Oral Diseases
The term Potentially Malignant Disorders was recommended to refer to precancer as it conveys that not all disorders described under this term may transform into cancer.  - Warnakulasuriya et al 2007

White patch or plaque that cannot be characterized clinically or pathologically as any other disease. - WHO 1973

Leukoplakia should be used to recognize white plaques of questionable risk having excluded (other) known diseases or disorders that carry no increased risk of cancer.

It is to be noted that a lesion of leukoplakia is non-scrappable.

A fiery red patch that cannot be characterized clinically or pathologically as any other definable disease.  - WHO 1973

Oral Submucous Fibrosis
It is an insidious chronic disease affecting any part of the oral cavity and sometimes the pharynx. Although occasionally preceded by and/or associated with vesicle formation, it is always associated with a juxta- epithelial inflammatory reaction followed by a fibro-elastic change of the lamina propria with epithelial atrophy leading to stiffness of the oral mucosa and causing trismus and inability to eat.
- Pindborg and Associates

A cyst is defined as ' a pathological cavity having fluid, semifluid or gaseous contents and which is not created by the accumulation of pus'. Most cysts, but not all, are lined by epithelium. - Kramer, 1974

Oncology: the study of neoplasms

Neoplasm: an uncontrolled new growth of tissue

Tumor: a localized swelling, may or may not be a true neoplasm

Hyperplasia: An increase in the size of a tissue or organ due to an increase in the number of component cells

Hypertrophy: an increase in the size of a tissue or organ due to an increase in the size of component cells

Cancer: a general term for all malignant neoplasms

Carcinoma: a malignant epithelial neoplasm

Sarcoma: a malignant mesenchymal (connective tissue) neoplasm

Hamartoma: a developmental defect characterized by an overgrowth of tissues normal to the organ in which it arises

Teratoma: a neoplasm composed of multiple tissues foreign to the organ in which it arises; may be benign or malignant