Pannus is an abnormal growth of fibrovascular or granulation tissue. It is not a standalone disease but a clinical sign that results from an underlying medical condition. This tissue growth can develop in various parts of the body, disrupting normal function and structure. Its formation is most often linked to chronic inflammatory processes and can lead to a range of complications.
Pannus Formation in the Body
Pannus can manifest in several distinct locations throughout the body, with the most common sites being the joints, eyes, and abdomen. Though the term “pannus” is used for all three, the biological processes and implications vary significantly between them.
In the joints, this growth is known as articular pannus and is a characteristic feature of inflammatory arthritis. It originates from the synovium, the thin membrane lining the joints. Chronic inflammation causes this lining to thicken and transform into an invasive tissue mass that spreads across the surface of the articular cartilage. This aggressive tissue is composed of fibroblast-like cells and inflammatory cells that release enzymes capable of eroding both cartilage and the underlying bone.
Within the eye, corneal pannus involves the growth of a tissue film containing blood vessels across the cornea, which is normally clear and devoid of vasculature. As this fibrovascular tissue extends over the cornea, it can obstruct light, leading to hazy or blurred vision and, in severe cases, significant sight impairment.
A different form of this condition is abdominal pannus, often called an apron belly. This term describes a hanging flap of skin and subcutaneous fatty tissue on the lower abdomen. Unlike the inflammatory pannus in joints and eyes, this type is not an invasive, destructive tissue. A less common manifestation can occur on prosthetic heart valves, where the tissue growth can interfere with the valve’s function.
Underlying Causes of Pannus Growth
Articular pannus is most associated with rheumatoid arthritis (RA), an autoimmune disease where the body’s immune system mistakenly attacks the joint lining. This immune response triggers chronic inflammation, leading to the proliferation of synovial tissue that evolves into pannus. The presence of cytokines and other inflammatory proteins fuels this growth, which actively damages joint structures. Other inflammatory conditions, such as psoriatic arthritis and lupus, can also lead to the formation of this destructive joint tissue.
The growth of corneal pannus is a reaction to chronic inflammation or injury to the eye’s surface. One frequent cause is the improper or prolonged use of contact lenses, which can lead to oxygen deprivation and irritation, prompting blood vessels to grow into the cornea. Infections, such as trachoma or keratitis, and other inflammatory eye diseases can also provoke this response, creating a film of tissue that clouds the cornea.
In contrast, abdominal pannus is not caused by an inflammatory disease but by physical changes related to body weight. It is primarily the result of significant obesity, where the accumulation of excess fat in the abdominal area stretches the skin over time. It can also appear after a person experiences massive and rapid weight loss, as the skin may lack the elasticity to retract to its former size, leaving a hanging apron of tissue.
Symptoms and Diagnostic Methods
In the joints, articular pannus manifests with symptoms characteristic of rheumatoid arthritis, including persistent joint pain, swelling, and stiffness. Affected joints may feel warm to the touch, exhibit a reduced range of motion, and a doctor might feel a “spongy” texture over the joint during a physical exam. For diagnosis, imaging tests like ultrasound or MRI are used to visualize the thickened synovial tissue and any damage to cartilage and bone.
When pannus develops on the eye, symptoms can include redness, a persistent feeling that something is in the eye, and progressively blurred or hazy vision. In some cases, the growth of blood vessels on the corneal surface may be visible upon close inspection. An ophthalmologist diagnoses corneal pannus using a slit-lamp examination, which provides a magnified view of the eye’s structures, allowing for detailed assessment of the abnormal tissue.
Abdominal pannus presents with physical discomfort due to the overhanging skin flap. This can lead to skin irritation, chafing, and the development of rashes or fungal and bacterial infections within the skin fold where moisture can become trapped. Diagnosis is made through a straightforward clinical assessment and physical examination by a healthcare provider, who will evaluate the size and condition of the tissue.
Medical and Surgical Interventions
For articular pannus resulting from rheumatoid arthritis, medical treatment focuses on suppressing the overactive immune system. This is achieved with medications such as Disease-Modifying Antirheumatic Drugs (DMARDs) and biologic agents, which target the inflammatory pathways that fuel pannus development. In cases where the tissue has caused significant joint damage or pain, a surgical procedure called a synovectomy may be performed to remove the inflamed synovial lining.
The management of corneal pannus aims to reduce inflammation and prevent further growth that could impair vision. Topical corticosteroids or other anti-inflammatory eye drops are often the first line of treatment. If vision is severely affected or the growth does not respond to medication, surgical options like a superficial keratectomy to remove the tissue layer or laser therapy to close off the invading blood vessels may be considered.
Treating an abdominal pannus involves both non-surgical and surgical strategies. Non-surgical management includes maintaining meticulous hygiene to prevent skin infections in the fold and pursuing weight loss through diet and exercise. For individuals with a large or problematic pannus, a surgical procedure known as a panniculectomy can be performed to remove the excess hanging skin and fat, which can improve comfort and mobility.