What condition is characterized by a sebaceous gland filling with a thick fluid?

A sebaceous cyst, also known as an epidermal cyst, is a condition characterized by the accumulation of thick fluid, which is often composed of sebum, a substance produced by sebaceous glands. These cysts typically arise when the sebaceous gland becomes obstructed, causing the sebum to build up and form a lump under the skin. The cyst is usually filled with a cheesy, keratinous material that can vary in consistency.

Keloids are abnormal growths of scar tissue that develop at the site of an injury. They are not related to sebaceous gland function and do not involve cyst formation. Acrochordons, commonly referred to as skin tags, are benign growths of skin that occur with friction but do not involve glands or fluid accumulation. Basal cell carcinoma is a type of skin cancer that arises from basal cells of the epidermis and does not relate to sebaceous glands or cyst formation.

Understanding the nature of sebaceous cysts helps in recognizing their appearance, causes, and treatment options, distinguishing them from other skin conditions.