by Jason Wasserman MD PhD FRCPC
February 27, 2023
Lichenoid mucositis is a pattern of inflammation characterized by large numbers of immune cells and tissue damage on the inside of the mouth. This pattern of inflammation can be seen in a variety of immune-mediated conditions, drug reactions, and chemical exposures.
Lichenoid mucositis is associated with red or white patches in the mouth that are usually painful and can be accompanied by other symptoms, such as burning, itching, and difficulty swallowing.
The exact cause of lichenoid mucositis is unknown but this pattern of inflammation is associated with immune-mediated conditions such as lichen planus and pemphigoid. Lichenoid mucositis can also be caused by drug reactions, chemical exposures, and infections.
Lichenoid mucositis is associated with a wide variety of drugs with the most common being nonsteroidal anti-inflammatory drugs (NSAIDs), antihypertensives, and antimalarials. Other types of drugs associated with this pattern of inflammation include anti-anxiety medications, antibiotics, antifungals, antidiabetics, anticonvulsants, antiretrovirals, and biologic agents.
Lichenoid mucositis is associated with dental agents such as metal fillers (e.g. mercury or gold) or non-metal agents such as acrylate compounds. This pattern of inflammation is also associated with flavoring agents such as cinnamon (especially cinnamon-flavored gum), mint, and menthol.
Lichenoid mucositis on its own is not a cancerous condition. However, if the condition persists for a long time it can lead to a precancerous disease called dysplasia. Dysplasia can only be diagnosed after a biopsy is performed and the tissue is examined under a microscope by a pathologist.
The diagnosis of lichenoid mucositis is usually based on the characteristic appearance of red patches in the oral cavity in combination with a biopsy of the affected tissue, which is examined under a microscope by a pathologist.
When examined under the microscope, a large number of immune cells, in particular lymphocytes and plasma cells, will be seen just under the surface of the tissue. Pathologists often describe these immune cells as showing a ‘band-like’ pattern of infiltration because the cells are arranged in a long ‘band’ or row. These immune cells are seen just below a thin layer of tissue called the squamous epithelium that covers the inside of the mouth. In lichenoid mucositis, the immune cells damage the squamous epithelium. This can result in an irregular or ‘saw-tooth’ interface between the squamous epithelium and the immune cells. Damaged squamous cells called dyskeratotic cells or Civatte bodies may also be seen.