Psoriatic Arthritis Differential Diagnosis Table

Psoriatic Arthritis Differential Diagnosis Table:

Psoriatic Arthritis, as the name suggests, is a kind of arthritis having a rash similar to psoriasis rash. It is an immune-related disease. It develops when the body’s protective mechanism (immune system) mistakenly identifies the body’s healthy cells and tissue as foreign material and then starts fighting against them, resulting in damage to normal cells and tissues of the body.
It causes the participation of one or more joints, fingers, or nails at a time. It usually presents with painful and stiffened joints with swollen joints and fingers. Nail discoloration, pitting, and crumbling usually occur. There is a raised, red rash, itchy plaques, and papules with grayish or silvery-white scale on elbows, knees, or scalp. The psoriatic rash can coexist with arthritis or may present before or after the arthritis.
It is usually diagnosed on history and clinical examination. Radiological tests such as X-rays, MRI, and Ultrasound are also helpful to see the bone and underlying disease. There is no definite treatment for this disease. But anti-rheumatic, steroid creams, and drugs to treat psoriasis, splints, exercise, physiotherapy are also helpful in relieving the symptoms of psoriatic arthritis. Joint replacement surgery can also be performed in severe cases.

How To Distinguish Psoriatic Arthritis from Other Diseases

Distinguish Reactive Arthritis from Psoriatic Arthritis – Diagnosis

Reactive Arthritis is an arthritis that develops in different joints of the body in reaction to an infection in another organ of the body. Symptoms include pain, inflammation, and rigidity in any joint but commonly affect the feet, knee joint, and hip joint. It can also cause conjunctivitis and urethritis. The features that distinguish them from Psoriatic Arthritis are:

• Neither of them is communicable, but reactive arthritis develops in people who have sexually transmitted diseases.
• Reactive arthritis is caused in response to an infection in the body while psoriatic arthritis is caused in people who are suffering from psoriasis.
• Although both are autoimmune diseases and both can relapse, reactive arthritis is mostly self-limiting while psoriatic arthritis has a longer course and can cause permanent disability in some cases.

It is simply diagnosed on a history of an infection and arthritis symptoms. Blood tests, radiological examination are also helpful. Antibiotics, Anti-inflammatory, Immunosuppressive, and corticosteroids are helpful in treatment.

Distinguish Ankylosing Spondylitis from Psoriatic Arthritis – Diagnosis

Ankylosing Spondylitis is basically inflammation or arthritis of joints and ligaments of the back, although it may affect other joints of the body. Symptoms are severe back pain, mostly when the body is in a rest position, stiffness in joints of the back which is more on waking up. Other symptoms include fatigue, fever, anorexia, or skin problems. The features that differentiate ankylosing spondylitis from psoriatic arthritis are:

• Ankylosing Spondylitis is a disease that mainly affects the spine, and the patient feels relieved while bending forward. In contrast to that, psoriatic arthritis mainly affects knees, hip joint, elbows, fingers, and feet joints, but the base of the spine can also be affected.
• Ankylosing Spondylitis doesn’t have skin lesions or nails involvement, while psoriatic arthritis has typical shiny, erythematous, inflamed skin lesions with white scales.
• Although both are autoimmune diseases related to the HLA-B27 factor, it is more common in ankylosing spondylitis as compared to psoriatic arthritis.

Ankylosing Spondylitis is diagnosed on a history of chronic back pain, blood tests, and x-rays of the spine show a typical ‘bamboo spine’ appearance. Treatment options include steroids, pain relievers, anti-rheumatic drugs, physiotherapy, and surgery.

Distinguish Osteoarthritis from Psoriatic Arthritis – Diagnosis

Osteoarthritis is a common form of arthritis resulting in the degeneration of bones and cartilage of joints. It can affect any joint, but knee, hip, and hand joints are more prone to this form of arthritis. The patient presents with painful joint movement, stiffness at rest, inflammation, cracking sounds on bending, and bone spurs. The feature which distinguishes osteoarthritis from psoriatic arthritis are:

• Osteoarthritis is a disease where bones and cartilages dissolve over time while Psoriatic arthritis is a disease in which the body’s defense system fights against normal cells.
• Although both can occur at any age, osteoarthritis seems to increase with age while psoriatic arthritis can occur at a much younger age.
• Both diseases can involve any joint, but osteoarthritis usually involves big joints while psoriatic arthritis tends to involve smaller joints.
• On X-rays, osteoarthritis has osteophytes, subcondral sclerosis, and narrowing of joint space while Psoriatic Arthritis has a ‘pencil in cup’ appearance.

Osteoarthritis is diagnosed on history, clinical examination, and X-rays of joints. Treatment options include exercise, physiotherapy, NSAIDs, pain relievers, and surgery.

Distinguish Rheumatoid Arthritis from Psoriatic Arthritis – Diagnosis

Rheumatoid Arthritis is an immune-related disorder that mainly affects joints. The symptoms of rheumatoid arthritis include morning stiffness, symmetrical involvement of joints of hands and feet, pain, and swelling in more than one joint. Extra-articular symptoms include scleritis, episcleritis, lung fibrosis, pulmonary nodule, rheumatoid nodule, and CVS diseases. The features that distinguish rheumatoid arthritis from psoriatic arthritis are:

• Rheumatoid Arthritis typically involves bilateral joints involvement while psoriatic arthritis has asymmetrical involvement of joints.
• Rheumatoid Arthritis has HLA DRB1 gene involvement while Psoriatic Arthritis has HLA B27 gene involvement.
• Rheumatoid arthritis skin lesions include single or multiple nodules of varying size and shape caused by friction or pressure on the skin while psoriatic arthritis has skin lesions similar to psoriatic lesion.

Rheumatoid nodule is diagnosed on history and clinical examination, blood tests, and radiological tests include X-rays, MRI, and ultrasound. Treatment options are; Anti-rheumatoid drugs, corticosteroids, NSAIDs, and painkillers are helpful in treatment.

Distinguish Gout from Psoriatic Arthritis – Diagnosis

Gout is a composite and common form of arthritis that can affect any joint but mainly involves the big toe of the foot. It is caused due to an increased level of uric acid in the blood resulting in the aggregation of uric acid crystals in and around the joint. Symptoms of gout include sudden, intense pain, and inflammation of joints. The features that distinguish gout from psoriatic arthritis are:

• Gout is a disease caused by the dietary intake of protein products, yogurt, sweets, and starch-containing products while Psoriatic arthritis is an autoimmune disease.
• Although both diseases are painful, but pain in gout is so intense that it affects the sleep cycle.
• Both diseases can involve many joints, but Gout mainly involves the big toe while Psoriatic arthritis involves knees, elbows, joints of hands and feet and is unlikely to involve only the big toe.

Gout is diagnosed on history, examination, uric acid levels, and X-rays. Treatment options include the avoidance of food containing proteins, NSAIDs, and steroids can be given.

Distinguish Systemic Lupus Erythematosus from Psoriatic Arthritis – Diagnosis

Systemic Lupus Erythematosus (SLE) is an immune-mediated disease that can affect many organs or organ systems at a time. It mostly causes damage to the skin, blood cells, kidneys, nervous system, and joints. Symptoms include fever, skin rashes, inflammation, arthritis, and tiredness. The features that differentiate SLE from Psoriatic Arthritis are:

• Systemic Lupus Erythematosus has a typical butterfly-shaped rash which is absent in Psoriatic arthritis.
• SLE is non-erosive, that means it affects joints but it doesn’t cause loss of bone and cartilage while Psoriatic arthritis causes loss of bone and cartilage.
• Both diseases are autoimmune, but SLE is associated with HLA-DRB1 while psoriatic arthritis is associated with HLA-B27.

SLE is diagnosed on history, clinical examination, blood and urine tests for ANA and Anti-smith antibodies and X-rays.

Distinguish Septic Arthritis from Psoriatic Arthritis – Diagnosis

Septic arthritis is a sepsis of joints caused by bacteria, fungi, or viruses. Symptoms are those of infection and arthritis, e.g., high temperature with rigors and chills, and swollen, immobile, hot, red, painful joints. The features that distinguish septic arthritis from psoriatic arthritis are:

• Septic arthritis is caused by infection while psoriatic arthritis is an autoimmune disease caused in people with psoriasis.
• On examination, septic arthritis has effusion in joints with immobility while psoriatic arthritis has painful and inflamed joints with skin lesions as present in psoriasis.
• Septic arthritis, once treated with antibiotics, is unlikely to occur again while psoriatic arthritis can show flare-ups again and again.

It is diagnosed on a history of fever and joint pain, clinical examination, blood tests, and X-rays. It is treated with antibiotics and joint fluid aspiration.

Distinguish Pseudogout from Psoriatic Arthritis – Diagnosis

Pseudogout is a joint disease caused by the aggregation of calcium pyrophosphate crystals (CPP) in the joints. Symptoms of pseudogout include inflammation, redness, tenderness, and pain in various joints. It commonly affects knees, and less commonly hands, shoulders, wrists, and ankles. The features that distinguish pseudogout from psoriatic arthritis are:

• Pseudogout is caused mainly by the accumulation of CPP crystals in the joint while psoriatic arthritis is an immune-related disease caused in patients with psoriasis.
• Pseudogout only has arthritis symptoms while psoriatic arthritis, in addition to arthritis, has skin lesions.
• Pseudogout has narrowing of joint space with sub-cortical geode formation while psoriatic arthritis has a typical ‘pencil in cup’ appearance.

It is diagnosed by history and clinical examination while confirmation is done by the examination of joint fluid aspiration. Treatment options are; rest and painkillers and anti-inflammatory drugs.

Important Red Flags of Psoriatic Arthritis

Any person who has signs of psoriasis is at great risk of developing psoriatic arthritis later in life, so they should be aware of any symptoms related to joint pain and immediately consult a doctor. It is not a reversible disease, but early treatment should be done to improve symptoms and quality of life. If psoriatic arthritis is left untreated, it can lead to permanent disability of joints.