Psoriatic Arthritis

Psoriatic Arthritis


Hello everyone. My name is Dr. Prateek Chaudhary. I’m a Duke Rheumatology fellow, and today we will be discussing psoriatic arthritis. Throughout this presentation, psoriatic arthritis will be abbreviated as PSA. Today we have six learning objectives. 1. Understand the epidemiology of PSA. 2. Appreciate the CASPAR criteria for the diagnosis of PSA. 3. Learn the five different types of PSA. 4. Appreciate the clinical and radiographic features of PSA. 5. Compare and contrast PSA from RA and, finally, 6. Treatment Strategies for PSA. Psoriatic arthritis is one of four different diseases we know as sero-negative spondyloarthropathies. These include ankylosing spondylitis, reactive arthritis, and enteropathic arthritis, which is associated with inflammatory bowel disease. Psoriatic arthritis is an inflammatory arthritis associated with the skin condition psoriasis, which is described as a red scaly rash that can affect the extensor surfaces, flexural areas, palms, soles, and nails. An example of a psoriatic rash on an individual’s elbow appears in the accompanying figure. There are several subtypes of psoriasis. Psoriasis vulgaris is the most common subtype associated with PSA. When you see a patient whom you suspect has a PSA, and you don’t see psoriatic lesions, look closely. Psoriasis can hide between gluteal folds and behind the ears and can be very easy to miss. Keep in mind, however, that the musculoskeletal manifestations of psoriatic arthritis can sometimes appear before the skin lesions. There’s no consensus in literature as to the prevalence of PSA, but it is generally accepted that up to one-third of psoriatic patients may experience PSA, with men and women usually equally affected. Several groups have developed diagnostic criteria for PSA. One of the most recent criteria gaining popularity is the CASPAR criteria, which carries a specificity of 99% and a sensitivity of 92% for psoriatic arthritis. CASPAR stands for the classification criteria for psoriatic arthritis. The CASPAR criteria requires evidence of inflammatory articular disease in a joint, spine, or entheses, where entheses is defined as a site of insertion of tendon into bone. In addition, three points or more are needed from the following categories. 1. There must be evidence of psoriasis. This can be current psoriasis, a personal history of psoriasis, or a family member, namely the first or second-degree relative with a history of psoriasis. Evidence of current psoriasis is worth two points, while the others in this category are worth one point. The diagnosis of psoriasis should be confirmed or visualized by either a dermatologist or rheumatologist. 2. Psoriatic nail dystrophy. This includes onycholysis, pitting or hyperkeratosis of the nail or nail bed. 3. Negative rheumatoid factor. 4. Dacylitis, which is namely a current or history of a swollen joint. 5. Radiographic evidence of just articular new bone formation seen as ill-defined ossification in your joint margins on plain films of the hands and feet. Examples of some of these are seen in the forthcoming slides. Again, enthesitis is inflammation at the site of a tendon insertion into bone. The Achilles and plantar fascia are the most common sites involved. While it is often visible on plain radiographs, sometimes enthesitis can be very subtle. Ultrasound may be useful for the diagnosis of enthesitis, though it is not currently used in routine practice. Within the world of psoriatic arthritis, there are five subtypes. These include oligoarthritis. This Subtype encompasses about 70% of psoriatic arthritis and is often associated with less than or equal to four joints. Number two is polyarthritis. This subtype affects 15%. This can be very difficult to distinguish from rheumatoid arthritis. It is often symmetric, unlike the oligoarticular type. Number three is the distal joint disease affecting 5%, and number four is spondyloarthritis. This is a subtype that affects the spine predominantly. 5% of those with psoriatic arthritis are of the subtype, this characterized mainly by asymmetry. For example, only one sacroiliac joint involved. This is in contrast to ankylosing spondylitis where you often see both SI joints involved. In addition, skip lesions of the entire spine may be present. Finally, spondyloarthritis is a subtype most often associated with another subtype of psoriatic arthritis. And the final type of psoriatic arthritis is arthritis mutilans. This occurs in about 5% and is known as the most destructive form. It is important to note that patients may present with one type of psoriatic arthritis but later develop another type. The most common presentation is for an individual to go from one of the oligoarticular type to the polyarticular type as the years go on and damage to joints accumulate. The following slides represent some classic images of PSA. The first slide is an image portraying dactylitis, otherwise known as a sausage digit. In this image, dactylitis is portrayed in the second toe. The sausage digit most often affects a toe, but the finger can be involved as well. Joints with dactylitis are more likely to develop erosions. In this image, you can see early evidence of nail bed separation known as onycholysis. Psoriatic arthritis can affect the nail in many ways. The American College of Rheumatology Image Bank has some great pictures of this with links on the left-hand portion of this slide. One of the nail manifestations of PSA is nail pits, sharp depressions in the nail plate due to shredding of nail plate cells. Imagine taking a pin and pricking a nail several times. Another manifestation is onycholysis, a separation of the nail from its bed. It can be hard to distinguish onycholysis from a nail fungal infection. Other manifestations include nail bed hyperkeratosis, nail crumbling, and splinter hemorrhages. I focus on nails in psoriatic arthritis, because severe nail involvement is associated with worse skin and joint disease. There are several classic radiographic findings in PSA. Links to the ACR Image Bank are on the left portion of the slide. In PSA you can see erosive changes and new bone formation in distal joints occurring at the same time. This is in contrast to rheumatoid arthritis, which erodes bone, and osteoarthritis in which extra bone is formed as spurs. In PSA, both processes tend to work simultaneously. Another radiographic abnormality is the pencil and cup deformity. This abnormality is most commonly seen in the finger and is secondary to erosion of bone with subsequent narrowing or tapering of the middle bone like a pencil, creating the resultant cup-shaped distortion of the end bone at the joint. You can also see fluffy periostosis, which manifests itself as inflammation of the periosteum with ill-defined borders, new bone formation at the site of the entheses and, finally, sacroiliitis which is inflammation of the sacroiliac joints. Sacroiliitis is demonstrated by the MRI findings on the lower left-hand portion of the slide. Sacroiliitis and PSA is a harbinger of a poor clinical prognosis. In this MRI image, the right SI joint is actively inflamed. Distinguishing psoriatic arthritis from rheumatoid arthritis can sometimes be difficult, but here are some clinical comparisons of the two arthritides. Rheumatoid factor is usually negative in PSA and positive in RA. Women are more likely afflicted with RA, whereas the general distribution is equal in PSA. PSA tends to manifest in a ray-like asymmetric distribution. For instance, an entire finger or toe being involved, while RA tends to be see more in a symmetric distribution. For instance, all the MCP joints in both hands. In psoriatic arthritis, you will sometimes see a bluish or purplish discoloration over the affected joint, which is not usually seen in RA. Finally, if there is evidence of inflammatory spine disease, think of psoriatic arthritis, as rheumatoid arthritis tends to spare the spine. Lastly, if something doesn’t make sense or the diagnosis is in question, reevaluate, and don’t forget to consider osteoarthritis and gout in the differential. You should also screen psoriatic arthritis patients for the following– Iritis, urethritis, bowel disease, and for cardiac abnormalities, such as dilatation at the base of the aortic route, which is associated with HLA-B27 positivity and coronary artery disease. There are several treatment modalities for psoriatic arthritis. Non-steroidal anti-inflammatory drugs, or NSAIDs, are considered the cornerstone of therapy, mostly extrapolating from trials on ankylosing spondylitis. NSAIDs include things like Naproxen, ibuprofen, meloxicam, diclofenac, and many others. Corticosteroids are also very helpful, including intra-articular steroid injections for mono- or oligoarticular arthritis and also for tendinitis or enthesitis. However, be wary of systemic steroids due to the theoretical possibility of skin disease flare upon withdrawal. DMARDs, also known as disease modifying antirheumatic drugs, can also be used. DMARDs used in PSA include methotrexate, sulfasalazine, leflunomide, and cyclosporine. Finally, antitumor necrosis factor therapy may be highly effective in PSA as it is for rheumatoid arthritis. FDA approved therapies include etanercept, infliximab, and adalimumab. The following few slides contain reference materials as well as citations for images from this presentation. Links to some great PSA images are again available on the American College of Rheumatology Image Bank website.

Leave a Reply

Your email address will not be published. Required fields are marked *