Epithelial dysplasia is the sum of various disturbances of epithelial

Epithelium

Epithelium is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue. Epithelial tissues line the cavities and surfaces of structures throughout the body, and also form many glands. Functions of epithelial cells include secretion, selective...

 proliferation and differentiation as seen microscopically. Individual cellular features of dysplasia

Dysplasia

Dysplasia , is a term used in pathology to refer to an abnormality of development. This generally consists of an expansion of immature cells, with a corresponding decrease in the number and location of mature cells. Dysplasia is often indicative of an early neoplastic process...

 are called epithelial atypia.

The changes that occur in epithelial dysplasia include:

• Drop-shaped rete processes
• Basal cell hyperplasia
  Hyperplasia
  Hyperplasia means increase in number of cells/proliferation of cells. It may result in the gross enlargement of an organ and the term is sometimes mixed with benign neoplasia/ benign tumor....
  
  
• Irregular epithelial stratification
• Nuclear hyperchromatism
• Increased nuclear-cytoplasmic ratio
  NC ratio
  The nuclear-cytoplasmic ratio is a measurement used in cell biology...
  
  
• Increased normal and abnormal mitosis
• Enlarged nucleoli
• Individual cell keratinization
• Loss or reduction of cellular cohesion
• Cellular pleomorphism
  Pleomorphism (cytology)
  Pleomorphism is a term used in histology and cytopathology to describe variability in the size and shape of cells and/or their nuclei. It is a feature characteristic of malignant neoplasms....
  
  
• Loss of basal cell polarity
• Anisocytosis
• koilocytosis

Epithelial cell dysplasia is divided into three categories of severity: mild, moderate, and severe.
Epithelial dysplasia becomes microinvasive squamous cell carcinoma

Squamous cell carcinoma

Squamous cell carcinoma , occasionally rendered as "squamous-cell carcinoma", is a histologically distinct form of cancer. It arises from the uncontrolled multiplication of malignant cells deriving from epithelium, or showing particular cytological or tissue architectural characteristics of...

once the tumor begins to invade nearby tissue.