Pannus is an abnormal layer of fibrovascular tissue or

granulation tissue Granulation tissue is new connective tissue and microscopic blood vessels that form on the surfaces of a wound during the healing process. Granulation tissue typically grows from the base of a wound and is able to fill wounds of almost any siz ...

. Common sites for pannus formation include over the cornea, over a joint surface (as seen in

rheumatoid arthritis Rheumatoid arthritis (RA) is a long-term autoimmune disorder that primarily affects joints. It typically results in warm, swollen, and painful joints. Pain and stiffness often worsen following rest. Most commonly, the wrist and hands are invol ...

), or on a prosthetic heart valve. 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 Panniculus, often incorrectly referred to as pannus, is a medical term describing a dense layer of fatty tissue, consisting of excess subcutaneous fat within the lower abdominal region. Panniculi can form after rapid weight loss, as seen with st ...

(a hanging flap of tissue).

Pannus in rheumatoid arthritis

The term "pannus" is derived from the Latin for "tablecloth". Inflammation and exuberant proliferation of the synovium leads to formation of pannus and destruction of cartilage, bone, tendons, ligaments, and blood vessels. Basically, the hypertrophied synovium is called pannus. 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

, pannus tissue eventually forms in the

joint A joint or articulation (or articular surface) is the connection made between bones, ossicles, or other hard structures in the body which link an animal's skeletal system into a functional whole.Saladin, Ken. Anatomy & Physiology. 7th ed. McGraw- ...

affected by the disease, causing loss of

bone A bone is a rigid organ that constitutes part of the skeleton in most vertebrate animals. Bones protect the various other organs of the body, produce red and white blood cells, store minerals, provide structure and support for the body, ...

and cartilage. From Autoimmunity and Disease by Harley Y. Tse and Michail K. Shaw:

Pannus in ophthalmology

ophthalmology Ophthalmology ( ) is a surgical subspecialty within medicine that deals with the diagnosis and treatment of eye disorders. An ophthalmologist is a physician who undergoes subspecialty training in medical and surgical eye care. Following a medic ...

, pannus refers to the growth of blood vessels into the peripheral

cornea The cornea is the transparent front part of the eye that covers the iris, pupil, and anterior chamber. Along with the anterior chamber and lens, the cornea refracts light, accounting for approximately two-thirds of the eye's total optical ...

. In normal individuals, the cornea is avascular. Chronic local hypoxia (such as that occurring with overuse of

contact lenses Contact lenses, or simply contacts, are thin lenses placed directly on the surface of the eyes. Contact lenses are ocular prosthetic devices used by over 150 million people worldwide, and they can be worn to correct vision or for cosmeti ...

) or inflammation may lead to peripheral corneal vascularization, or pannus. Pannus may also develop in diseases of the corneal stem cells, such as aniridia. It is often resolved by

peritomy A peritomy is a procedure carried out during eye surgery, where an incision is made at the limbus in order to reflect the conjunctiva and Tenon's capsule of the eye, usually to expose the sclera and/or extraocular muscles for a variety of sur ...

References

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