by Jason Wasserman MD PhD FRCPC
November 30, 2024
A lymphoepithelial cyst is a benign (non-cancerous) growth commonly found in the head and neck but less commonly in other parts of the body. It is called “lymphoepithelial” because it comprises lymphoid tissue and epithelial cells.
Most lymphoepithelial cysts do not cause any symptoms and are discovered incidentally during a medical exam. However, if the cyst grows large enough, it may start to put pressure on surrounding tissues, causing discomfort or swelling. In this situation, patients may notice a lump in the neck, under the jaw, or mouth. Larger cysts in the mouth or throat may cause difficulty swallowing or speaking.
The exact cause of lymphoepithelial cysts is not entirely understood. Still, they are thought to develop when the normal drainage of fluid from lymphoid tissue is blocked, possibly due to inflammation or infection. These cysts are also associated with certain chronic conditions, such as autoimmune disorders, and can develop in individuals with HIV.
Lymphoepithelial cysts are often seen in people with HIV, and their presence can be a sign of the disease. They may also occur in individuals with autoimmune conditions, such as rheumatoid arthritis and Sjögren’s syndrome. Chronic inflammation of the salivary gland tissue can also lead to the formation of these cysts.
Lymphoepithelial cysts are benign, which means they are not cancerous. They do not spread to other body parts and typically do not pose a significant health risk. However, because they can sometimes resemble cancerous growths, your doctor will likely perform a biopsy or remove the cyst to confirm the diagnosis.
The diagnosis of a lymphoepithelial cyst is usually made after the cyst is removed and examined by a pathologist. The pathologist will examine the tissue under a microscope to confirm the presence of lymphoid and epithelial components, which is the cyst’s defining characteristic. Imaging studies, such as ultrasound, CT scans, or MRIs, may also evaluate the cyst before removal.
Under the microscope, lymphoepithelial cysts have distinct features. The cyst is lined by squamous cells, flat, scale-like cells that line many body parts. Surrounding the cyst are lymphoid cells, including a combination of B cells and T cells (types of immune cells). Round structures called lymphoid follicles, some containing germinal centers, may also be seen. The cyst’s contents may include fluid, protein material, or cellular debris.