Nuclear atypia, in which the nuclei of cells varies in size, any may be increased in size relative to the cytoplasm, shape, and may stain more intensely. There may also be more prominent nucleoli. Increased number of cells seen undergoing mitosis, including both normal and abnormal mitoses. Abnormal mitosis may be abnormally located, e.g. occurring in suprabasal cells (cell layers more superficial to the basal cell layer) or of abnormal form, e.g. "tri-radiate mitoses" (a cell splitting into 3 daughter cells rather than only 2)
Loss the normal organization of the epithelial layers. The distinction between the epithelial layers may be lost. Normally stratified squamous epithelium shows progressive changes in the form of cells from the basal to the superficial layers, with cells becoming more flat ("squames") towards the surface as a continuous maturation process. In dysplastic epithelium, cells may become vertically orientated rather than becoming flat towards the surface. There may be abnormal keratinization, where keratin is formed below the normal keratin layer. This can occur in individual cells or groups of cells, forming an intraepithelial keratin pearl. There may be an increase in the number of basal cells, and they may lose their cellular orientation (losing their polarity and long axis). Alteration of the normal epithelial-connective tissue architecture - the rete pegs may become "drop shaped". wider at their base than more superficially.Generally, dysplasia is subjectively graded by pathologists into mild, moderate or severe dysplasia. This requires experience as it is a difficult skill to learn.
This condition is not considered to be a true idiopathic leukoplakia since the causative agent has been identified. It is one of the most common oral lesions associated with HIV infection, along with pseudomembraneous candidiasis. The appearance of the lesion often heralds the transition from HIV to acquired immunodeficiency syndrome (AIDS). Syphilitic leukoplakia
This term refers to a white lesion associated with syphilis, specifically in the tertiary stage of the infection. It is not considered to be a type of idiopathic leukoplakia, since the causative agent Treponema pallidum is known. It is now rare, but when syphilis was more common, this white patch usually appeared on the top surface of the tongue and carried a high risk of cancerous changes. It is unclear if this lesion was related to the condition itself or whether it was caused by the treatments for syphilis at the time. Esophagus
Leukoplakia of the esophagus is rare compared to oral leukoplakia. The relationship with esophageal cancer is unclear because the incidence of esophageal leukoplakia is so low. It usually appears as a small, nearly opaque white lesion that may resemble early esophageal squamous cell carcinoma. The histologic appearance is similar to oral leukoplakia, with hyperkeratosis and possible dysplasia. Bladder
In the context of lesions of the mucous membrane lining of the bladder, leukoplakia is a historic term for a visualized white patch which histologically represents keratinization in an area of squamous metaplasia.