What Does Squamous Cell in Situ Indicate?


Quick Answer

Squamous cell carcinoma in situ indicates an early stage of skin cancer that only exists in the outer layer of skin. This condition appears as a red, scaly or crusted plaque that occurs on the skin or mucous membranes. It is usually caused by prolonged sun exposure, according to MedicineNet.

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Full Answer

Squamous cells refer to the uppermost cells in the epidermis or outer layer of skin. The epidermis is a very thin layer of skin that protects the deeper layers of skin and bodily organs from environmental hazards. The epidermis contains three types of cells: squamous, basal and melanocytes. Squamous cells are flat, exist in the outer part of the epidermis, and have a high rate of cellular turnover. Basal cells are in the lower part of the epidermis but gradually move up to replace the squamous cells that shed. Melanocytes produce the pigment melanin, which gives the skin its color, explains American Cancer Society.

The term "in situ" means that the cancerous squamous cells remain in the epidermis and have not spread to the deeper layers of the skin. The dermis is the layer of skin below the epidermis. It is much thicker than the epidermis and contains collagen, a protein that provides skin with elasticity and strength. Hair follicles, blood vessels, sweat glands and nerves all exist in the dermis. The last layer of skin is the subcutis. The subcutis conserves heat, protects organs from injury and absorbs shocks. Most health professionals recommend removing and treating squamous cell carcinoma in situ to prevent it from spreading to other cells in the epidermis or deeper layers of the skin, according to American Cancer Society.

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