Undifferentiated connective tissue disease overview

# Overview
The concept of undifferentiated connective tissue disease(UCTD) came into existence in 1980 when LeRoy et al found out some disease entities which don't qualify the criteria of definite connective tissue disease but resemble rheumatological diseases. The patients with UCTD presents with signs and symptoms of connective tissue diseases like arthritis, Raynaud's phenomenon, Dry-mouth, dry eyes.Undifferentiated connective tissue disorder(UCTD) are actually a group of disorders that are unclassified in other connective tissue disorders. UCTD may be classified according to criteria developed by American College of Rheumatology(ACR) and European League Against Rheumatism(EULAR) : early Raynaud's phenomenon, early inflammatory arthritis that is not classified as rheumatoid arthritis, some manifestations same as that of inflammatory myopathy, systemic lupus erythematosus, Sjogren's syndrome, vasculitis, serositis, or interstitial lung disease which don't meet diagnostic criteria for each of them and early scleroderma.The exact pathogenesis of undifferentiated connective tissue disorder(UCTD) is not fully understood. It is understood that UCTD is the result of autoimmune process and occurs in phases: Initial phase: which is asymptomatic and absence of auto-antibodies and second phase with the presence of auto-antibodies. The second phase is usually triggered by the environmental factors, such as infection. Auto-antibodies appear before the symptoms of the disease.The time between the two is variable. Autoantibodies usually seen in UCTD with positive correlation are antibodies against C1q ,Anti heat shock protein(hsp)-65, Anti hsp 60. The clinical picture involves the overlap of symptoms of other rheumatological disease but not completing the criteria of their diagnosis. More studies are needed to find the pathogenesis of UCTD.The cause of undifferentiated connective tissue disease has not been identified.UCTD is differentiated with other causes of arthritis and rash such as SLE, Sjogren's syndrome, Rheumatoid arthritis. Not enough epidemiological studies have been done but about 25% of the presentation of more than 1 year resembles connective tissue disorder.UCTD is differentiated with other causes of arthritis and rash such as SLE, Sjogren's syndrome, Rheumatoid arthritis.There are no established risk factors for UCTD.The symptoms of undifferentiated connective tissue disease(UCTD) usually are similar to connective tissue diseases but couldn't complete the criteria for their definitive diagnosis. If left untreated, 24.3-33% of patients with UCTD may progress to develop manifestations of well defined connective tissue disease such as systemic lupus erythematosus, rheumatoid arthritis, Sjogren's syndrome. Common complications of UCTD include Interstitial lung disease- Non specific interstitial pneumonia, atherosclerosis. Depending on the extent of the UCTD at the time of diagnosis, the prognosis may vary. However, the prognosis is generally regarded as good. The presence of interstitial lung disease is associated with a particularly good prognosis among patients with UCTD rather than being idiopathic.Patients with undifferentiated connective tissue disease (UCTD) may have a positive history of Raynaud's phenomenon, arthritis, photosensitivity, sicca symptoms, pleuritis/pericarditis. The common symptoms of UCTD include arthralgia, dry eyes, rash, photosensitivity and dry mouth. Less common symptoms of UCTD include fever, pleuritic chest pain and seizures. Patients with UCTD usually appear well but can present with low-grade fever, Raynaud's phenomenon, rash and Erythema nodosum in the skin examination. On examining HEENT,Conjunctivitis, Uveitis, Keratoconjunctivitis sicca, dry-mouth can be seen. In the neck, lymphadenopathy can be seen. Rhonchi, Wheezing, pleural friction rub and Pericardial friction rub can be heard on auscultation.On examining abdomen, tenderness in the right/left upper/lower abdominal quadrant and hepatomegaly are noted. In the back, tenderness over lumbar vertebrae can occur and sacral edema may be seen.Rashes can be seen in the genitourinary exam. The patient can have altered mental statuswith psychosis and peripheral neuropathy and Pitting/non-pitting edema of the lower extremities. Laboratory findings suggestive of undifferentiated connective tissue disease include Leukopenia,increased erythrocyte sedimentation rate, C-reactive protein, Antinuclear antibodies, anti DNA antibodies, anti Ro/SSA antibodies and anti-RNP antibodies.The pharmacologic medical therapy is recommended based on the rheumatic disease pattern manifested by the patient such as methotrexate in those exhibiting arthritis and dermatitis. Supportive therapy includes; avoiding cold exposure in those experiencing Raynaud's phenomenon, avoiding sun in photosensitivity, non-steroidal anti-inflammatory drugs for pain control, sunscreen used for photosensitivity, and emollients for dry skin, rash.The mainstay of treatment for undifferentiated connective tissue disorder is medical therapy. Surgery is rarely needed for patients for surgical biopsy in case of diagnosis.The feasibility of surgery depends on the prognosis at diagnosis.

# Historical Perspective
Undifferentiated connective tissue disease (UCTD) was first explored by LeRoy et al in 1980.

# Classification
Undifferentiated connective tissue disorder (UCTD) are actually a group of disorders that are unclassified in other connective tissue disorders. UCTD may be classified according to the criteria developed by American College of Rheumatology (ACR) and European League Against Rheumatism (EULAR) into: early Raynaud's phenomenon, early inflammatory arthritis that is not classified as rheumatoid arthritis, some manifestations same as that of inflammatory myopathy, systemic lupus erythematosus, Sjogren's syndrome, vasculitis, serositis, or interstitial lung disease which don't meet diagnostic criteria for each of them and early scleroderma.

# Pathophysiology
The exact pathogenesis of undifferentiated connective tissue disorder (UCTD) is not fully understood. It is understood that UCTD is the result of an autoimmune process and occurs in phases: Initial phase: which is asymptomatic and is characterized by absence of auto-antibodies and second phase which is characterized by the presence of auto-antibodies. The second phase is usually triggered by the environmental factors, such as infection. Auto-antibodies appear before the symptoms of the disease.The time between the two is variable. Autoantibodies usually seen in UCTD with positive correlation are antibodies against C1q ,Anti heat shock protein (hsp)-65, Anti hsp 60. The clinical picture involves the overlap of symptoms of other rheumatological disease but not completing the criteria of their diagnosis. More studies are needed to find the pathogenesis of UCTD.

# Causes
The cause of undifferentiated connective tissue disease has not been identified.

# Differentiating UTCD from Other Diseases
UCTD should be differentiated from other causes of arthritis and rash such as SLE, Sjogren's syndrome, Rheumatoid arthritis.

# Epidemiology and Demographics
There is absence of any epidemiological study regarding UTCD till date but its estimated that UCTD represents 60% of the disease with undifferentiated onset.

# Risk Factors
There are no established risk factors for UCTD.

# Screening
There is insufficient evidence to recommend routine screening for undifferentiated connective tissue disease.

# Natural History, Complications, and Prognosis
The symptoms of undifferentiated connective tissue disease (UCTD) usually are similar to connective tissue diseases but couldn't complete the criteria for their definitive diagnosis. If left untreated, 24.3-33% of patients with UCTD may progress to develop manifestations of well defined connective tissue disease such as systemic lupus erythematosus, rheumatoid arthritis, Sjogren's syndrome. Common complications of UCTD include Interstitial lung disease- Non specific interstitial pneumonia, atherosclerosis. Depending on the extent of the UCTD at the time of diagnosis, the prognosis may vary. However, the prognosis is generally regarded as good. The presence of interstitial lung disease is associated with a particularly good prognosis among patients with UCTD rather than being idiopathic.

# Diagnosis

## History and Symptoms
Patients with undifferentiated connective tissue disease (UCTD) may have a positive history of Raynaud's phenomenon, arthritis, photosensitivity, sicca symptoms, pleuritis/pericarditis. The common symptoms of UCTD include arthralgia, dry eyes, rash, photosensitivity and dry mouth. Less common symptoms of UCTD include fever, pleuritic chest pain and seizures.

## Physical Examination
Patients with UCTD usually appear well but can present with low-grade fever, Raynaud's phenomenon, rash and Erythema nodosum. On HEENT examination, Conjunctivitis, Uveitis, Keratoconjunctivitis sicca, dry-mouth can be seen. In the neck, lymphadenopathy can be seen. Rhonchi, Wheezing, pleural friction rub and Pericardial friction rub can be heard on auscultation. On examining abdomen, tenderness in the right/left upper/lower abdominal quadrant and hepatomegaly may be noted. In the back, tenderness over the lumbar vertebrae can occur and sacral edema may be seen. Rash can be seen in the genitourinary exam. The patient can have altered mental status with psychosis and peripheral neuropathy and pitting/non-pitting edema of the lower extremities.

## Laboratory Findings
Laboratory findings suggestive of undifferentiated connective tissue disease include Leukopenia,increased erythrocyte sedimentation rate, C-reactive protein, Antinuclear antibodies, anti DNA antibodies, anti Ro/SSA antibodies, and anti-RNP antibodies.

## CT scan
There are no CT scan findings associated specifically with undifferentiated connective tissue disease.

## MRI
There are no MRI findings associated specifically with undifferentiated connective tissue disease.

## Other Imaging Findings
There are no other imaging findings associated specifically with undifferentiated connective tissue disease.

## Other Diagnostic Studies
There are no other diagnostic studies associated specifically with undifferentiated connective tissue disease.

# Treatment

## Medical Therapy
The pharmacologic medical therapy is recommended based on the rheumatic disease pattern manifested by the patient such as methotrexate in those exhibiting arthritis and dermatitis. Supportive therapy includes; avoiding cold exposure in those experiencing Raynaud's phenomenon, avoiding sun in photosensitivity, non-steroidal anti-inflammatory drugs for pain control, sunscreen used for photosensitivity, and emollients for dry skin and rash.

## Prevention
There are no established measures for the prevention of undifferentiated connective tissue disease.