Pannus is an abnormal layer of fibrovascular tissue or granulation tissue. Common sites for pannus formation include over the cornea, over a joint surface (as seen in rheumatoid arthritis), or on a prosthetic heart valve.[ Farlex Partner Medical Dictionary © Farlex 2012] Pannus may grow in a tumor-like fashion, as in joints where it may erode articular cartilage and bone.
In common usage, the term pannus is often used to refer to a panniculus (a hanging flap of tissue).
Pannus in rheumatoid arthritis
The term "
pannus" is derived from the Latin for "tablecloth". Chronic inflammation and exuberant proliferation of the synovium leads to formation of
pannus and destruction of cartilage, bone, tendons, ligaments, and blood vessels.
Pannus tissue is composed of aggressive macrophage- and fibroblast-like mesenchymal cells, macrophage-like cells and other inflammatory cells that release collagenolytic enzymes.
In people suffering from rheumatoid arthritis, pannus tissue eventually forms in the joint affected by the disease, causing bone erosion and cartilage loss via release of IL-1, prostaglandins, and substance P by macrophages.
Pannus in ophthalmology
In
ophthalmology,
pannus refers to the growth of blood vessels into the peripheral
cornea. In normal individuals, the cornea is
Blood vessel. Chronic local hypoxia (such as that occurring with overuse of
contact lenses) or inflammation may lead to peripheral corneal vascularization, or pannus. Pannus may also develop in diseases of the corneal
, such as
aniridia. It is often resolved by
peritomy.
