Squamous tissue is a type of epithelial tissue and is classified as either simple squamous or stratified squamous. Epithelial tissue is the body tissue that lines structures within the body such as glands. It lies on top of connective tissue and is made up of cells that secrete, absorb and transport, depending upon the type of epithelial tissue.
Simple squamous tissue looks like thin, flat circles tightly formed together. It is named simple squamous tissue because it forms in a single layer and can be penetrated. Simple squamous tissue functions include filtration or diffusion and are most often found in capillaries and the pulmonary alveoli which are located in the lungs. This is made easier because the flat cells ease friction and allow fluids to flow back and forth between the membranes.
Stratified squamous epithelial tissue is more comprehensive than simple squamous tissue but does include the same flat, circular cells in its base layer. Subsequent layers of stratified squamous tissue adhere to the base layer to preserve the structure. Though not all layers will look thin and flat because inner layers can actually be different types of tissue, the medical community names tissue based on the outer layer so the entire section will be named stratified squamous tissue.
Additional sub-categories of stratified squamous tissue are based on whether keratin, which is a fibrous protein, is present. Tissues with keratin are protected from drying out by a protective surface. Examples include skin, the tongue and lips. Stratified squamous tissues that do not contain keratin use secretions from the body to keep from drying out. Examples include the cornea, esophagus, vagina, and rectum.
There are a variety of squamous cell carcinomas that can develop. These include: adenoid, clear cell, spindle cell, signet-ring, and basal. Carcinomas can either be specific to one site or invasive, which means it spreads to other parts of the body. Typical symptoms are lesions, ulcers, tumors, and sun damaged skin.
Treatments for squamous cell carcinomas vary depending on the area where the cancer is present. Diagnosis begins with a biopsy which involves removing a small area of cells or tissue. The biopsy is viewed under a microscope to determine if any abnormal cells are present. Most squamous cell carcinomas are removed via surgery and the patient is monitored periodically to ensure no additional cancerous cells are found. External beam radiotherapy, which is a type of radiation, may also be employed to treat squamous cell carcinomas affecting areas of the body deeper than the skin's surface.