Pannus is a medical term describing an abnormal layer of tissue formation that proliferates in an area where it does not normally belong. This tissue growth is generally a consequence of chronic inflammation or structural changes within the body. The formation acts as an invasive layer of cells that can impair the normal function of an organ or anatomical structure. The nature of this growth varies significantly depending on its location, ranging from highly destructive inflammatory tissue to an apron-like fold of excess skin and fat.
Pannus Formation in Joints
Pannus formation in joints is primarily associated with conditions like Rheumatoid Arthritis (RA). In this context, pannus is a hyperplastic, thickened layer of synovial tissue that develops due to persistent inflammation of the joint lining. The normally thin synovial membrane becomes engorged with a dense collection of inflammatory cells, including macrophages and fibroblast-like synoviocytes.
This destructive tissue layer adheres to and invades the adjacent articular cartilage and subchondral bone. Cells within the pannus secrete high levels of destructive enzymes, such as matrix metalloproteinases and cathepsins. These enzymes cause the progressive erosion of cartilage and bone, leading to the characteristic joint damage seen in RA. The process results in loss of joint space and mobility, often beginning in smaller joints like the wrists and hands.
Corneal Pannus in the Eye
In the eye, pannus describes the invasion of blood vessels and fibrous tissue onto the surface of the cornea. This fibrovascular tissue typically originates from the limbus, the border between the cornea and the white part of the eye (sclera). The primary cause is chronic local hypoxia or inflammation, which triggers the body to grow vessels into the clear tissue in an attempt to supply it with oxygen and nutrients.
A frequent cause of corneal pannus is the prolonged or improper wear of contact lenses, which can deprive the cornea of necessary oxygen. Other inflammatory conditions, such as chronic dry eye, infections, or trauma can also lead to this vascular encroachment. The growth of this opaque, vascularized tissue impairs the cornea’s clarity, leading to impaired vision as light is scattered and blocked.
Abdominal Pannus and Skin Folds
The term pannus is also commonly used to refer to a large, apron-like fold of excess skin and subcutaneous fat that hangs over the lower abdomen, often called a panniculus. This structural type of pannus typically develops as a result of significant weight gain or following massive weight loss where excess skin remains. Unlike the inflammatory types found in joints and the eye, the abdominal pannus is a non-inflammatory, adipose tissue mass.
This hanging flap of tissue can extend down to cover the groin, thighs, or even the knees, impacting a person’s quality of life and mobility. The fold creates a warm, moist environment susceptible to chronic issues like intertrigo, a rash caused by skin-on-skin friction and moisture. This can lead to persistent skin infections and hygiene difficulties.
Diagnostic Procedures and Management
The methods for identifying and managing pannus vary widely, reflecting the different tissues and pathologies involved.
Joint Pannus Management
Diagnosis of joint pannus relies on advanced imaging techniques, such as ultrasound and Magnetic Resonance Imaging (MRI), which visualize the thickened synovial tissue and detect early signs of joint erosion. Management focuses on halting the underlying inflammatory process and preventing joint destruction. The primary medical strategy involves Disease-Modifying Antirheumatic Drugs (DMARDs), including biological agents, which suppress the immune system and slow tissue progression.
For severe, late-stage joint damage, surgical intervention may be necessary. A procedure called synovectomy can be performed to remove the hyperplastic synovial tissue, or a joint replacement may be required to restore mobility.
Corneal Pannus Management
Corneal pannus is diagnosed through a comprehensive eye examination using a slit-lamp microscope, which allows visualization of the ingrowth of blood vessels onto the corneal surface. Treatment initially targets the underlying cause, which may involve discontinuing or refitting ill-fitting contact lenses to improve oxygen flow. Topical medications, such as corticosteroids, are commonly prescribed to reduce inflammation and suppress vascular growth.
Abdominal Pannus Management
Diagnosis of the abdominal pannus requires a physical examination to assess the size and extent of the overhanging skin fold. Management begins with non-surgical strategies, including weight management and meticulous hygiene practices to control intertrigo and skin infections. When the pannus causes chronic medical issues like persistent infections or mobility impairment, a surgical procedure called a panniculectomy may be performed. This operation removes the excess skin and fat for functional improvement, distinguishing it from a purely cosmetic tummy tuck.