Image type: Raynaud’s vasculitis
Body site: Hands and fingers
Description: Mixed connective-tissue disease (MCTD) is a disorder with features of systemic sclerosis (SSc), lupus erythematosus, and polymyositis. U1-ribonucleoprotein (RNP) antibodies are a specific marker of the disease. MCTD is considered a distinct syndrome and should not be confused with other connective-tissue disease overlap syndromes with features of various connective-tissue diseases. The course of MCTD is chronic and usually milder than other connective-tissue diseases. Although MCTD is a distinct clinical entity, a subgroup of patients may evolve into having another connective-tissue disease.
Early indications of mixed connective tissue disease may include:
- General feeling of being unwell. This malaise may be accompanied by increased fatigue and a mild fever.
- Cold and numb fingers. One of the most common early indicators is known as Raynaud’s phenomenon in which the fingers feel cold and numb, often in response to cold or stress. Fingers may turn white and then purplish blue when the blood vessels constrict. After warming, the blood vessels relax, blood flow resumes, and the fingers turn red. Toes also can be affected.
- Swollen fingers. Many people who have mixed connective tissue disease experience swelling in their hands and fingers, sometimes to the point where the fingers resemble sausages.
- Muscle and joint pain. MCTD also can result in muscle aches, joint swelling, and pain. In some cases, the joints may become deformed, similar to what is seen in rheumatoid arthritis.
- Skin that looks shiny on the hands and forearm.
The prognosis for patients with MCTD is generally better than that of patients with systemic lupus erythematosus (SLE), SSc, and dermatomyositis. About 4% of patients die, usually as a result of pulmonary hypertension, nephritis, myocarditis, or widespread vasculitis. In one case series, solid tumors developed in approximately 10% of patients. Women are affected by MCTD more often than men. The female-to-male ratio is 4:1.
MCTD commonly affects individuals aged 30-50 years and also children, with the latter experiencing more severe symptoms due to increased likelihood of cardiac and renal involvement. Although MCTD-related thrombocytopenia is rare in adults, children may experience marked thrombocytopenia.
Usually, patients with MCTD are presented with Raynaud’s phenomenon. Headaches may occur, and patients may report fatigue. While myalgia and arthralgia are important early symptoms of pediatric-onset MCTD, many adolescent girls report pain along with fatigue. The Raynaud’s phenomenon should hasten evaluation. Capillary findings should also be evaluated because they may correlate with the development of scleroderma spectrum disorders.
Diagnosis: Diagnosis of MCTD poses challenges due to the sequential occurrence of symptoms from three distinct diseases over an extended period. Healthcare providers typically examine for indicators such as swollen hands and joints, conducting blood tests to identify specific antibodies associated with MCTD. There are four characteristic features that point towards MCTD instead of another connective tissue disorder:
- The presence of a particular antibody, anti-U1-RNP (ribonucleoprotein), in high concentrations in blood tests serves as a distinguishing factor for MCTD.
- Additionally, the absence of severe kidney and central nervous system complications, commonly observed in SLE patients, is indicative of MCTD.
- MCTD may exhibit unique features, including severe arthritis and pulmonary hypertension, distinguishing it from both SLE and scleroderma.
- Moreover, the presence of the Raynaud phenomenon, swollen hands, or puffy fingers, occurring in only around 25% of individuals with SLE, further aids in the differentiation and diagnosis of MCTD.
Despite these distinctive features, an accurate diagnosis of MCTD may require several years of observation and testing.
Treatment: The treatment of MCTD is a comprehensive approach aimed at managing symptoms and suppressing the autoimmune response. Medications such as nonsteroidal anti-inflammatory drugs (NSAIDs), corticosteroids, and immunosuppressive agents are commonly used to control inflammation and alleviate joint and muscle pain. Disease-modifying anti-rheumatic drugs (DMARDs) may also be used to modify the course of the disease. Physical therapy and occupational therapy can help address joint stiffness and improve overall function. Regular monitoring, lifestyle modifications, and nutritional support are important parts of the treatment plan. It is essential to collaborate with healthcare providers, especially rheumatologists, for personalized management and adjustments to the treatment strategy as needed.