psoriatic arthritis
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Psoriatic arthritis is a long-term inflammatory arthritis that occurs in people affected by the
autoimmune disease An autoimmune disease is a condition arising from an abnormal immune response to a functioning body part. At least 80 types of autoimmune diseases have been identified, with some evidence suggesting that there may be more than 100 types. Nearly a ...
psoriasis Psoriasis is a long-lasting, noncontagious autoimmune disease characterized by skin plaque, raised areas of abnormal skin. These areas are erythema, red, pink, or purple, Xeroderma, dry, itchy, and scaly. Psoriasis varies in severity from small ...
. The classic feature of psoriatic arthritis is swelling of entire fingers and toes with a sausage-like appearance. This often happens in association with changes to the nails such as small depressions in the nail (pitting), thickening of the nails, and detachment of the nail from the nailbed. Skin changes consistent with
psoriasis Psoriasis is a long-lasting, noncontagious autoimmune disease characterized by skin plaque, raised areas of abnormal skin. These areas are erythema, red, pink, or purple, Xeroderma, dry, itchy, and scaly. Psoriasis varies in severity from small ...
(e.g., red, scaly, and itchy plaques) frequently occur before the onset of psoriatic arthritis but psoriatic arthritis can precede the rash in 15% of affected individuals. It is classified as a type of seronegative spondyloarthropathy.
Genetics Genetics is the study of genes, genetic variation, and heredity in organisms.Hartl D, Jones E (2005) It is an important branch in biology because heredity is vital to organisms' evolution. Gregor Mendel, a Moravian Augustinians, Augustinian fr ...
are thought to be strongly involved in the development of psoriatic arthritis.
Obesity Obesity is a medical condition, sometimes considered a disease, in which excess Adipose tissue, body fat has accumulated to such an extent that it may negatively affect health. People are classified as obese when their body mass index (BMI) ...
and certain forms of psoriasis are thought to increase the risk. Psoriatic arthritis affects up to 30% of people with psoriasis and occurs in both children and adults. Approximately 40–50% of individuals with psoriatic arthritis have the HLA-B27 genotype. The condition is less common in people of Asian or African descent and affects men and women equally.


Signs and symptoms

Pain, swelling, or stiffness in one or more joints is commonly present in psoriatic arthritis. Psoriatic arthritis is inflammatory, and affected joints are generally red or warm to the touch. Asymmetrical oligoarthritis, defined as inflammation affecting two to four joints during the first six months of disease, is present in 70% of cases. However, in 15% of cases, the arthritis is symmetrical. The joints of the hand that is involved in psoriasis are the proximal interphalangeal (PIP), the distal interphalangeal (DIP), the metacarpophalangeal (MCP), and the wrist. Involvement of the distal interphalangeal joints (DIP) is a characteristic feature and is present in 15% of cases. In addition to affecting the joints of the hands and wrists, psoriatic arthritis may affect the fingers, nails, and skin. Sausage-like swelling in the fingers or toes, known as dactylitis, may occur. Psoriasis can also cause changes to the nails, such as pitting or separation from the nail bed, onycholysis,
hyperkeratosis Hyperkeratosis is thickening of the stratum corneum (the outermost layer of the Epidermis (skin), epidermis, or skin), often associated with the presence of an abnormal quantity of keratin,Kumar, Vinay; Fausto, Nelso; Abbas, Abul (2004) ''Robbins ...
under the nails, and horizontal ridging. Psoriasis classically presents with scaly skin lesions, which are most commonly seen over extensor surfaces such as the scalp, natal cleft and umbilicus. In psoriatic arthritis, pain can occur in the area of the
sacrum The sacrum (plural: ''sacra'' or ''sacrums''), in human body, human anatomy, is a large, triangular bone at the base of the vertebral column, spine that forms by the fusing of the sacral vertebrae (S1S5) between ages 18 and 30. The sacrum situ ...
(the lower back, above the tailbone), as a result of sacroiliitis or spondylitis, which is present in 40% of cases. Pain can occur in and around the feet and ankles, especially enthesitis in the Achilles tendon (inflammation of the Achilles tendon where it inserts into the bone) or plantar fasciitis in the sole of the foot. Along with the above-noted pain and inflammation, there is extreme exhaustion that does not go away with adequate rest. The exhaustion may last for days or weeks without abatement. Psoriatic arthritis may remain mild or may progress to more destructive joint disease. Periods of active disease, or flares, will typically alternate with periods of remission. In severe forms, psoriatic arthritis may progress to arthritis mutilansDavidson, Stanley
Davidson's principles and practice of medicine
Churchill Livingstone/Elsevier, p. 1096, 2010. . Accessed 2016-11-12.
which on X-ray gives a "pencil-in-cup" appearance. Because prolonged inflammation can lead to joint damage, early diagnosis and treatment to slow or prevent joint damage is recommended.


Causes

The exact causes are not yet known, however silica dust exposure has been identified in Australia and a number of genetic associations have been identified in a genome-wide association study of psoriasis and psoriatic arthritis including HLA-B27.


Diagnosis

Magnetic resonance images of the fingers in psoriatic arthritis. Shown are T1-weighted (a) pre-contrast and (b) post-contrast coronal images. Enhancement of the proximal_interphalangeal_(PIP)_and_Interphalangeal_articulations_of_hand.html" ;"title="Interphalangeal articulations of hand">proximal interphalangeal (PIP) and distal_interphalangeal_(DIP)_joints_is_seen,_indicating_active_ distal_interphalangeal_(DIP)_joints_is_seen,_indicating_active_synovitis">Interphalangeal_articulations_of_hand">distal_interphalangeal_(DIP)_joints_is_seen,_indicating_active_synovitis_(inflammation_of_the_synovial_membrane;_large_arrows)._There_is_joint_space_narrowing_with_bone_proliferation_at_the_third_PIP_joint_and_erosions_are_present_at_the_fourth_DIP_joint_(white_circle)._Extracapsular_enhancement_(small_arrows)_is_seen_Human_anatomical_terms.html" ;"title="synovitis.html" ;"title="Interphalangeal articulations of hand">distal interphalangeal (DIP) joints is seen, indicating active synovitis">Interphalangeal articulations of hand">distal interphalangeal (DIP) joints is seen, indicating active synovitis (inflammation of the synovial membrane; large arrows). There is joint space narrowing with bone proliferation at the third PIP joint and erosions are present at the fourth DIP joint (white circle). Extracapsular enhancement (small arrows) is seen Human anatomical terms">medial to the third and fourth PIP joints, indicating probable enthesitis (inflammation of a tendon insertion). file:Psoriatic arthritis ankle ar1934-3.gif, Sagittal plane, Sagittal magnetic resonance images of the ankle region in psoriatic arthritis. (a) Short tau inversion recovery (STIR) image, showing high signal intensity at the
Achilles tendon The Achilles tendon or heel cord, also known as the calcaneal tendon, is a tendon at the back of the lower leg, and is the thickest in the human body. It serves to attach the plantaris muscle, plantaris, gastrocnemius muscle, gastrocnemius (calf ...
insertion ( enthesitis, thick arrow) and in the synovium of the ankle joint (synovitis, long thin arrow). Bone marrow edema is seen at the tendon insertion (short thin arrow). (b, c) T1 weighted images of a different section of the same patient, before (panel b) and after (panel c) intravenous contrast injection, confirm inflammation (large arrow) at the enthesis and reveal bone erosion at tendon insertion (short thin arrows). There is no definitive test to diagnose psoriatic arthritis. Symptoms of psoriatic arthritis may closely resemble other diseases, including
rheumatoid arthritis Rheumatoid arthritis (RA) is a long-term autoimmune disorder that primarily affects synovial joint, joints. It typically results in warm, swollen, and painful joints. Pain and stiffness often worsen following rest. Most commonly, the wrist and ...
. A rheumatologist (a physician specializing in autoimmune diseases) may use physical examinations, health history, blood tests and x-rays to accurately diagnose psoriatic arthritis. Factors that contribute to a diagnosis of psoriatic arthritis include the following: * Psoriasis in the patient, or a family history of psoriasis or psoriatic arthritis. * A negative test result for rheumatoid factor, a blood factor associated with rheumatoid arthritis. * Arthritis symptoms in the distal Interphalangeal articulations of hand (the joints closest to the tips of the fingers). This is not typical of rheumatoid arthritis. * Ridging or pitting of fingernails or toenails ( onycholysis), which is associated with psoriasis and psoriatic arthritis. * Radiologic images demonstrating degenerative joint changes. Other symptoms that are more typical of psoriatic arthritis than other forms of arthritis include enthesitis (inflammation in the
Achilles tendon The Achilles tendon or heel cord, also known as the calcaneal tendon, is a tendon at the back of the lower leg, and is the thickest in the human body. It serves to attach the plantaris muscle, plantaris, gastrocnemius muscle, gastrocnemius (calf ...
(at the back of the heel) or the plantar fascia (bottom of the feet)), and dactylitis (sausage-like swelling of the fingers or toes). File:Psoriatic arthritis digit ar1934-2.gif, Magnetic resonance image of the index finger in psoriatic arthritis (mutilans form). Shown is a T2 weighted fat suppressed sagittal image. Focal increased signal (probable erosion) is seen at the base of the middle phalanx (long thin arrow). There is synovitis at the proximal interphalangeal joint (long thick arrow) plus increased signal in the overlying soft tissues indicating
edema Edema, also spelled oedema, and also known as fluid retention, dropsy, hydropsy and swelling, is the build-up of fluid in the body's tissue. Most commonly, the legs or arms are affected. Symptoms may include skin which feels tight, the area ma ...
(short thick arrow). There is also diffuse bone edema (short thin arrows) involving the head of the proximal phalanx and extending distally down the shaft. File:Psoriatic arthritis dactylitis ar1934-4.gif, Magnetic resonance images of the fingers in psoriatic arthritis. Shown are T1 weighted axial (a) pre-contrast and (b) post-contrast images exhibiting dactylitis due to flexor tenosynovitis at the second finger with enhancement and thickening of the tendon sheath (large arrow). Synovitis is seen in the fourth proximal interphalangeal joint (small arrow). File:Psoriatic arthritis spine ar1934-6.gif, (a) T1-weighted and (b) short tau inversion recovery (STIR) magnetic resonance images of lumbar and lower thoracic spine in psoriatic arthritis. Signs of active inflammation are seen at several levels (arrows). In particular, anterior spondylitis is seen at level L1/L2 and an inflammatory Andersson lesion at the upper vertebral endplate of L3. File:Sacroiliitis MRI ar1934-5.gif, Magnetic resonance images of sacroiliac joints. Shown are T1-weighted semi-coronal magnetic resonance images through the sacroiliac joints (a) before and (b) after intravenous contrast injection. Enhancement is seen at the right sacroiliac joint (arrow, left side of the image), indicating active sacroiliitis.


Differential diagnosis

Several conditions can mimic the clinical presentation of psoriatic arthritis including
rheumatoid arthritis Rheumatoid arthritis (RA) is a long-term autoimmune disorder that primarily affects synovial joint, joints. It typically results in warm, swollen, and painful joints. Pain and stiffness often worsen following rest. Most commonly, the wrist and ...
, osteoarthritis,
reactive arthritis Reactive arthritis, also known as Reiter's syndrome, is a form of Inflammation, inflammatory arthritis that develops in response to an infection in another part of the body (cross-reactivity). Coming into contact with bacteria and developing an in ...
, gouty arthritis,
systemic lupus erythematosus Lupus, technically known as systemic lupus erythematosus (SLE), is an autoimmune disease in which the body's immune system mistakenly attacks healthy tissue in many parts of the body. Symptoms vary among people and may be mild to severe. Commo ...
, and
inflammatory bowel disease Inflammatory bowel disease (IBD) is a group of inflammation, inflammatory conditions of the colon (anatomy), colon and small intestine, Crohn's disease and ulcerative colitis being the principal types. Crohn's disease affects the small intestine a ...
-associated arthritis. In contrast to psoriatic arthritis, rheumatoid arthritis tends to affect the proximal joints (e.g., the metacarpophalangeal joints), involves a greater number of joints than psoriatic arthritis, and affect them symmetrically. Involvement of the spinal joints is more suggestive of psoriatic arthritis than rheumatoid arthritis. Osteoarthritis shares certain clinical features with psoriatic arthritis such as its tendency to affect multiple distal joints in an asymmetric pattern. Unlike psoriatic arthritis, osteoarthritis does not typically involve inflammation of the sacroiliac joint. Psoriatic arthritis sometimes affects only one joint and is sometimes confused for gout or
pseudogout Calcium pyrophosphate dihydrate (CPPD) crystal deposition disease, also known as pseudogout and pyrophosphate arthropathy, is a rheumatology, rheumatologic disease which is thought to be secondary to abnormal accumulation of calcium pyrophosphate ...
when this happens.


Classification

There are five main types of psoriatic arthritis: * Oligoarticular: This type affects around 70% of patients and is generally mild. This type does not occur in the same joints on both sides of the body and usually only involves fewer than 3 joints. * Polyarticular: This type accounts for around 25% of cases, and affects five or more joints on both sides of the body simultaneously. This type is most similar to
rheumatoid arthritis Rheumatoid arthritis (RA) is a long-term autoimmune disorder that primarily affects synovial joint, joints. It typically results in warm, swollen, and painful joints. Pain and stiffness often worsen following rest. Most commonly, the wrist and ...
and is disabling in around 50% of all cases. * Arthritis mutilans (): Affects less than 5% of patients and is a severe, deforming and destructive arthritis. This condition can progress over months or years causing severe joint damage. Arthritis mutilans has also been called chronic absorptive arthritis, and may be seen in
rheumatoid arthritis Rheumatoid arthritis (RA) is a long-term autoimmune disorder that primarily affects synovial joint, joints. It typically results in warm, swollen, and painful joints. Pain and stiffness often worsen following rest. Most commonly, the wrist and ...
as well. * Spondyloarthritis (): This type is characterized by stiffness of the neck or the sacroiliac joint of the spine, but can also affect the hands and feet, in a similar fashion to symmetric arthritis. * Distal interphalangeal predominant (): This type of psoriatic arthritis is found in about 5% of patients, and is characterized by inflammation and stiffness in the joints nearest to the ends of the fingers and toes. Nail changes are often marked.


Treatments

The underlying process in psoriatic arthritis is
inflammation Inflammation (from la, inflammatio) is part of the complex biological response of body tissues to harmful stimuli, such as pathogens, damaged cells, or irritants, and is a protective response involving immune cells, blood vessels, and mol ...
; therefore, treatments are directed at reducing and controlling
inflammation Inflammation (from la, inflammatio) is part of the complex biological response of body tissues to harmful stimuli, such as pathogens, damaged cells, or irritants, and is a protective response involving immune cells, blood vessels, and mol ...
. Milder cases of psoriatic arthritis may be treated with NSAIDs alone; however, there is a trend toward earlier use of disease-modifying antirheumatic drugs or biological response modifiers to prevent irreversible joint destruction.


Nonsteroidal anti-inflammatory drugs

Typically the medications first prescribed for psoriatic arthritis are
NSAID Non-steroidal anti-inflammatory drugs (NSAID) are members of a Indication (medicine), therapeutic drug class which Analgesic, reduces pain, Anti-inflammatory, decreases inflammation, Antipyretic, decreases fever, and Antithrombotic, prevents blo ...
s such as ibuprofen and naproxen, followed by more potent NSAIDs like diclofenac, indomethacin, and etodolac. NSAIDs can irritate the stomach and intestine, and long-term use can lead to gastrointestinal bleeding. Coxibs ( COX-2 inhibitors) e.g. Celecoxib or Etoricoxib, are associated with a statistically significant 50 to 66% relative risk reduction in gastrointestinal ulcers and bleeding complications compared to traditional NSAIDs, but carry an increased rate of cardiovascular events such as
myocardial infarction A myocardial infarction (MI), commonly known as a heart attack, occurs when Hemodynamics, blood flow decreases or stops to the coronary artery of the heart, causing ischemia, damage to the cardiac muscle, heart muscle. The most common symptom i ...
(MI) or heart attack, and
stroke A stroke is a disease, medical condition in which poor cerebral circulation, blood flow to the brain causes cell death. There are two main types of stroke: brain ischemia, ischemic, due to lack of blood flow, and intracranial hemorrhage, hemorr ...
. Both COX-2 inhibitors and other non-selective NSAIDS have potential adverse effects that include damage to the kidneys.


Disease-modifying antirheumatic drugs

These are used in persistent symptomatic cases without exacerbation. Rather than just reducing pain and inflammation, this class of drugs helps limit the amount of joint damage that occurs in psoriatic arthritis. Most DMARDs act slowly and may take weeks or even months to take full effect. Drugs such as methotrexate or leflunomide are commonly prescribed; other DMARDS used to treat psoriatic arthritis include cyclosporin, azathioprine, and sulfasalazine. According to a recent Cochrane review, low dose oral methotrexate was slightly more effective than placebos. Immunosuppressant drugs can also reduce psoriasis skin symptoms but can lead to liver and kidney problems and an increased risk of serious infection.


Biological response modifiers

A new class of therapeutics called biological response modifiers or biologics has been developed using
recombinant DNA Recombinant DNA (rDNA) molecules are DNA molecules formed by laboratory methods of genetic recombination (such as molecular cloning) that bring together genetic material from multiple sources, creating DNA sequence, sequences that would not othe ...
technology. Biologic medications are derived from living cells cultured in a laboratory. Unlike traditional DMARDS that affect the entire immune system, biologics target specific parts of the immune system. They are given by injection or intravenous (IV) infusion. Biologics prescribed for psoriatic arthritis are TNF-α inhibitors, including infliximab, etanercept, golimumab, certolizumab pegol and adalimumab, as well as the IL-12/ IL-23 inhibitor ustekinumab, and the IL-17a inhibitor secukinumab. Recently, the Jak inhibitor, tofacitinib (Xeljanz), was approved for the use in active psoriatic arthritis. Biologics may increase the risk of minor and serious infections. More rarely, they may be associated with nervous system disorders, blood disorders or certain types of cancer.


Phosphodiesterase-4 inhibitors

A first-in-class treatment option for the management of psoriatic arthritis is apremilast; a small molecule phosphodiesterase-4 inhibitor approved for use by the FDA in 2014. By inhibiting PDE4, an enzyme which breaks down
cyclic adenosine monophosphate Cyclic adenosine monophosphate (cAMP, cyclic AMP, or 3',5'-cyclic adenosine monophosphate) is a second messenger important in many biological processes. cAMP is a derivative of adenosine triphosphate (ATP) and used for intracellular signal transd ...
, cAMP levels rise, resulting in the down-regulation of various pro-inflammatory factors including TNF-α, interleukin 17 and interleukin 23, as well as the up-regulation of anti-inflammatory factor interleukin 10. It is given in tablet form and taken by mouth. Side effects include headaches, back pain, nausea, diarrhea, fatigue, nasopharyngitis and upper respiratory tract infections, as well as depression and weight loss. It was patented in 2014 and manufactured by Celgene. There is no current generic equivalent available on the market.


Other treatments

A review found tentative evidence of benefit of low level laser therapy and concluded that it could be considered for relief of pain and stiffness associated RA. Retinoid etretinate is effective for both arthritis and skin lesions. Photochemotherapy with methoxy psoralen and long-wave ultraviolet light (PUVA) are used for severe skin lesions. Doctors may use joint injections with
corticosteroid Corticosteroids are a class of steroid hormones that are produced in the adrenal cortex of vertebrates, as well as the synthetic analogues of these hormones. Two main classes of corticosteroids, glucocorticoids and mineralocorticoids, are involve ...
s in cases where one joint is severely affected. In psoriatic arthritis patients with severe joint damage orthopedic surgery may be implemented to correct joint destruction, usually with the use of a joint replacement. Surgery is effective for pain alleviation, correcting joint disfigurement, and reinforcing joint usefulness and strength.


Epidemiology

Seventy percent of people who develop psoriatic arthritis first show signs of
psoriasis Psoriasis is a long-lasting, noncontagious autoimmune disease characterized by skin plaque, raised areas of abnormal skin. These areas are erythema, red, pink, or purple, Xeroderma, dry, itchy, and scaly. Psoriasis varies in severity from small ...
on the skin, 15 percent develop skin psoriasis and arthritis at the same time, and 15 percent develop skin psoriasis following the onset of psoriatic arthritis. Psoriatic arthritis can develop in people who have any level severity of psoriatic skin disease, ranging from mild to very severe. Psoriatic arthritis tends to appear about 10 years after the first signs of
psoriasis Psoriasis is a long-lasting, noncontagious autoimmune disease characterized by skin plaque, raised areas of abnormal skin. These areas are erythema, red, pink, or purple, Xeroderma, dry, itchy, and scaly. Psoriasis varies in severity from small ...
. For the majority of people, this is between the ages of 30 and 55, but the disease can also affect children. The onset of psoriatic arthritis symptoms before symptoms of skin psoriasis is more common in children than adults. More than 80% of patients with psoriatic arthritis will have psoriatic nail lesions characterized by nail pitting, separation of the nail from the underlying nail bed, ridging and cracking, or more extremely, loss of the nail itself ( onycholysis). Enthesitis is observed in 30 to 50% of patients and most commonly involves the plantar fascia and Achilles’ tendon, but it may cause pain around the patella, iliac crest, epicondyles, and supraspinatus insertions Men and women are equally affected by this condition. Like
psoriasis Psoriasis is a long-lasting, noncontagious autoimmune disease characterized by skin plaque, raised areas of abnormal skin. These areas are erythema, red, pink, or purple, Xeroderma, dry, itchy, and scaly. Psoriasis varies in severity from small ...
, psoriatic arthritis is more common among Caucasians than African or Asian people.


References


External links


Psoriatic Arthritis
at Patient.info
Guidelines of care for the management of psoriasis and psoriatic arthritis
National Guideline Clearinghouse
US National Institute of Arthritis and Musculoskeletal and Skin Diseases
{{Diseases of the musculoskeletal system and connective tissue Arthritis Autoimmune diseases Psoriasis Rheumatology