OVERVIEW

What is connective tissue disease?

Connective tissue disease (CTD) is a general term for autoimmune disorders characterized by chronic inflammation of connective tissues, affecting multiple organs and systems^[1]. Connective tissues include muscles, joints, fascia, ligaments, blood vessels, etc. Its pathogenesis and etiology are complex and not yet fully understood, primarily related to genetic, environmental, and infectious factors^[2]. Common symptoms include Raynaud's phenomenon (color changes in extremities due to cold or other stimuli), joint swelling and pain, fever, and rashes^[3].

Connective tissue diseases are generally not completely curable, but symptoms can be alleviated through medication or surgery. With timely treatment, the prognosis is good. If left untreated, the disease may affect multiple systems and impair daily life.

Is connective tissue disease common? What types exist?

Yes, it is common. Connective tissue diseases encompass various disorders, with systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA) being the most prevalent. Statistics show that the prevalence of these two diseases in China is approximately 0.4%, meaning about 1 in 250 people may be affected^[4]. The condition is more common in women^[5]. The most common types include^[1]:

• Systemic lupus erythematosus (SLE): Affects the skin and joints, primarily presenting with annular erythema.
• Rheumatoid arthritis (RA): Affects the joints, mainly causing joint swelling, pain, and morning stiffness (joint stiffness upon waking, typically lasting over an hour before gradually improving).
• Dermatomyositis (DM): Affects the skin and muscles, characterized by red or purplish rashes.
• Systemic sclerosis (SSc): Affects the skin and internal organs, leading to skin hardening and organ dysfunction.
• Mixed connective tissue disease (MCTD): Exhibits symptoms of various connective tissue diseases (e.g., those mentioned above) but does not meet the diagnostic criteria for any single type.
• Sjögren's syndrome (SS): Affects exocrine glands (e.g., tear, sweat, and digestive glands), causing dryness in the mouth and eyes.

Which department should I visit for connective tissue disease?

Rheumatology and Immunology, Orthopedics, Dermatology

SYMPTOMS

What are the common symptoms of connective tissue diseases?

Connective tissue diseases are complex and involve multiple systems. The following are relatively common symptoms^[5]:

• Raynaud's phenomenon: In response to cold or other stimuli, the skin at the fingertips or toes turns white, cyanotic (bluish-purple), and then red.
• Joint symptoms: Swelling, pain, and weakness in the joints.
• Skin symptoms: Skin rashes, papules (visible small bumps), oral ulcers, etc.
• Fever: Body temperature usually exceeds 37.2°C.
• Other symptoms: Dry mouth or eyes, hair loss, etc.

Where do connective tissue diseases commonly occur?

They frequently affect the skin, joints, and muscles, but may also involve organs such as the heart and lungs, as well as blood vessels.

What complications can connective tissue diseases cause?

This disease may generally lead to the following complications^[6]:

• Interstitial lung disease: Connective tissue diseases can cause pulmonary fibrosis (increased fibrous connective tissue in the lungs and reduced functional cells), manifesting as difficulty breathing, coughing, etc.
• Acral necrosis: Connective tissue diseases can damage blood vessels, and vascular occlusion may lead to insufficient blood supply to the extremities, resulting in necrosis, which presents as ischemic pain.
• Gastroesophageal reflux disease (GERD): Connective tissue diseases can cause esophageal mucosal damage, leading to symptoms such as painful swallowing and a burning sensation in the stomach.

CAUSES

What are the common causes of connective tissue diseases?

The exact causes of connective tissue diseases are not yet fully understood, but they are generally believed to be related to the following factors^[2]:

• **Genetic factors**: Studies suggest that connective tissue diseases are hereditary. Mutations in certain genes (e.g., the FBN2 gene) can disrupt the normal structure of connective tissues, leading to disease.
• **Environmental factors**: Long-term exposure to radiation, air pollution, drugs, or chemicals can impair immune function (affecting both humoral and cellular immunity), increasing the risk of connective tissue diseases.
• **Infectious factors**: Infections caused by viruses, bacteria, or fungi can damage connective tissues and trigger connective tissue diseases.

Who is more likely to develop connective tissue diseases?

• **Individuals with a family history of connective tissue diseases**: Due to genetic predisposition, those with affected relatives have a higher risk.
• **People with prolonged radiation exposure**: Frequent UV exposure (e.g., outdoor workers) or radiotherapy patients are more susceptible due to chronic connective tissue irritation.
• **Chemical industry workers**: Long-term exposure to toxic chemicals at work can damage connective tissues, increasing disease risk.
• **Those with poor hygiene or weakened immunity**: Such individuals are more prone to infections (viral, bacterial, or fungal), which may trigger connective tissue diseases.

Are connective tissue diseases contagious?

No, connective tissue diseases are not contagious.

Are connective tissue diseases hereditary?

Yes. Family members have a significantly higher risk, as some connective tissue diseases are autosomal dominant disorders (a single mutated gene on an autosome suffices to cause the disease, with a 50% chance of inheritance)^[2].

DIAGNOSIS

How to diagnose connective tissue disease? What tests are needed?

Connective tissue diseases involve multiple systems. After collecting medical history (such as family history of connective tissue disease or systemic diseases) and physical examination, selective auxiliary tests are performed based on clinical symptoms for diagnosis.

Generally, the following tests are required^[3]:

• Physical examination: Checks for typical clinical symptoms such as skin/mucosal damage, joint swelling/pain, or Raynaud's phenomenon (color changes in extremities due to cold or other stimuli). These findings, combined with medical history, may suggest initial screening.
• Complete blood count (CBC): Measures hemoglobin levels and white/red blood cell/platelet counts. Patients may show reduced white/red blood cells or platelets.
• Blood biochemistry: Evaluates inflammatory markers like erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP), which increase during active disease. Liver function tests may reveal elevated serum transaminases, indicating liver damage.
• Urinalysis: Patients may exhibit proteinuria or hematuria.
• Serological immunology tests: Includes immunoglobulin levels, antinuclear antibody (ANA) panel, and rheumatoid factor (RF). Low immunoglobulin levels with positive ANA/RF confirm diagnosis.
• Imaging: Ultrasound, CT, or MRI assesses joint, bone, or visceral damage to evaluate severity.
• Biopsy: For complex cases, skin, synovial fluid, or organ biopsies may aid diagnosis.

Is connective tissue disease easily confused with other conditions? How to differentiate?

Connective tissue diseases must be distinguished from osteoarthritis and dermatitis.

Osteoarthritis: Shares symptoms like morning stiffness and joint swelling/pain, often mimicking rheumatoid arthritis. Serological tests help differentiate—osteoarthritis patients test negative for RF and typically affect older adults.

Dermatitis: Includes allergic or contact dermatitis. Dermatomyositis in connective tissue diseases presents with both skin inflammation and muscle symptoms (e.g., weakness, reduced muscle strength), unlike typical dermatitis, which causes itching and has clear allergic triggers.

TREATMENT

How to treat connective tissue disease?

The main treatment methods for connective tissue disease are medication and surgery.
Drug therapy is suitable for patients who need to control connective tissue disease and alleviate symptoms such as rashes and joint swelling and pain. Commonly used drugs include the following categories^[5]:

• Glucocorticoids: Have anti-inflammatory and immune-regulating effects. Common drugs include hydrocortisone and dexamethasone. Long-term use may cause infections, hypertension, and other symptoms.
• Immunosuppressants: Have anti-infection and abnormal immune response suppression effects. Common drugs include methotrexate and cyclophosphamide. Long-term use may cause diarrhea, leukopenia, and other symptoms.
• Nonsteroidal anti-inflammatory drugs (NSAIDs): Have anti-inflammatory and pain-relieving effects. Common drugs include aspirin and celecoxib. These drugs may cause dizziness, vomiting, bleeding, etc.
• Disease-modifying antirheumatic drugs (DMARDs): Generally used for connective tissue diseases such as rheumatoid arthritis. Common drugs include leflunomide. Long-term use may cause hypertension, abdominal pain, etc.

Surgical treatment is suitable for patients with severe joint dysfunction whose physical condition permits surgery. There are generally three types of surgeries^[6]:

• Synovectomy: Suitable for patients with synovial lesions. It can prevent further joint damage and alleviate joint swelling and pain. The surgery usually takes less than two hours, with recovery in one to two months.
• Joint release surgery: Suitable for patients with joint and surrounding soft tissue deformities. It can correct joint deformities. The surgery usually takes about two hours, with recovery in two to three months.
• Joint replacement surgery: Suitable for patients with joint deformities accompanied by unbearable pain. The diseased joint is replaced with an artificial joint. The surgery typically takes about two hours, with recovery in one month.

All the above surgeries carry risks of anesthesia and postoperative infection.

Can connective tissue disease be completely cured?

No. Timely treatment can control the condition and alleviate symptoms such as joint pain, but it cannot completely cure the disease.

DIET & LIFESTYLE

What should connective tissue disease patients pay attention to in their diet?

• Maintain a light diet, eat less greasy and spicy foods, and avoid or minimize strong tea, coffee, and cold or irritating foods like ice cream^[7], as these may worsen skin symptoms.
• Practice good food hygiene, wash hands before meals, and reduce the risk of bacterial infection.
• Increase intake of vitamins and protein by consuming fruits, vegetables, milk, eggs, lean meat, etc.

What precautions and care are needed after surgery for connective tissue disease?

• Family members should regularly turn the patient in bed to prevent pressure sores.
• Maintain a regular schedule, ensure adequate rest, avoid staying up late, and promote recovery.
• Take medications as prescribed, practice personal hygiene, avoid sharing personal items, and prevent infections.
• Since the disease cannot be completely cured, patients may experience anxiety. Distract yourself by listening to music or watching TV to relax.
• If the condition allows, engage in moderate exercise like walking or Tai Chi to strengthen the body and boost immunity.
• Stay warm, keep indoor temperatures around 25°C, and use warm or hot water for washing to avoid cold stimulation.

Does having a metal joint due to connective tissue disease affect travel on public transportation?

Since the patient has metal implants, security checks may cause issues. Upon discharge, ask the doctor to note "metal implants in the body" in the medical certificate and carry this document for security checks during travel.

Do connective tissue disease patients need follow-up examinations? How often?

Yes, regular follow-ups are necessary as advised by the doctor. Patients newly on medication should generally have check-ups every two weeks to monitor potential side effects. If the condition stabilizes, monthly check-ups are recommended, which can later extend to every six months if stability continues. Tests may include blood tests, liver function, and urinalysis. Since patients often have weakened immunity, wear a mask during hospital visits, maintain hygiene, and avoid contact with infectious individuals.

Does connective tissue disease affect fertility?

Yes, pregnancy is not recommended before the condition stabilizes.

Newly diagnosed connective tissue disease in pregnant women has a poor prognosis, possibly leading to miscarriage or even life-threatening risks. Patients with stable conditions have better pregnancy outcomes, but since the disease is often hereditary, their children are at high risk and should undergo regular check-ups^[8].

For example, systemic lupus erythematosus (SLE) patients should ensure the disease has been in remission for at least six months, have no severe organ damage, and take less than 15 mg of prednisone daily to safeguard fetal health. Pregnancy may trigger SLE flare-ups, worsening the condition, and early use of immunosuppressants can cause fetal abnormalities^[9].

Therefore, couples with connective tissue disease planning for children should wait until the condition stabilizes and consult a doctor for evaluation. If diagnosed after pregnancy, seek professional advice on whether to continue the pregnancy.

PREVENTION

Can Connective Tissue Diseases Be Prevented? How to Prevent Them?

The causes of connective tissue diseases are complex, and prevention or disease stabilization generally relies on maintaining good daily habits:

• Go to bed early and wake up early, maintain a positive mindset, engage in moderate physical exercise (such as walking, jogging, or tai chi) to boost immunity.
• Stay warm and practice good hygiene to avoid infections caused by bacteria, fungi, etc.
• Quit smoking and drinking, avoid prolonged sun exposure or use sun protection, and steer clear of toxic chemicals.
• If there is a family history of the disease, schedule regular check-ups.