PSORIATIC ARTHRITIS

Abdelrahman Amer Mousa

Resident of Rheumatology & Physical medicine

Mansoura University Hospital

How prevalent is psoriasis and psoriatic arthritis

in the general population???

•Epidemiologic studies suggest that the prevalence of psoriasis is

approximately 2% to 3%. Whites are affected

• (two times) more often than other ethnic groups. The estimates of

inflammatory arthritis accompanying

•psoriasis range from 7% to 42% (average 26%).

prevalence of arthritis is relatively equal between the sexes.

However, However, in patients with spinal involvement, the male to female

ratio is almost 3:1

. Men also tend to have a higher prevalence of DIP-only involvement,

whereas women tend to have a higher prevalence of symmetric

polyarthritis.

Most patients present between the ages of 35 and 50 years. However,

juvenile psoriatic arthritis is also well

recognized and usually presents between ages 9 and 12 years

Is there a relationship between the onset of

psoriasis and the onset of arthritis?

Psoriasis precedes arthritis by an average of 8 to 10 years in 67%

of patients.

Arthritis precedes psoriasis or occurs simultaneously in 33% of

patients, particularly in childhood and in older patients (>age 50

years).

What are the current classification criteria for psoriatic

arthritis?The CASPAR (Classification of Psoriatic Arthritis) criteria are:

1. Evidence of psoriasis (current, past, family): two points if current

history of psoriasis, one point others.

2. Psoriatic nail dystrophy: one point

3. Negative rheumatoid factor: one point.

4. Dactylitis (current, past history): one point.

5. Radiographic evidence of juxtaarticular new bone formation: one

point.

Three or more points have 99% specificity and 92% sensitivity for

diagnosis of psoriatic arthritis

Articular involvement

The majority have symmetric polyarthritis or asymmetric

oligoarthritis of the hands and feet. Often the DIP joints

become stiff, swollen, and tender in an asymmetric fashion.

When present, involvement of the DIP joints helps distinguish

psoriatic arthritis from rheumatoid arthritis, but sometimes

results in confusion with osteoarthritis or gout. Other

joints that are affected by psoriatic arthritis include the knees,

hips, and sternoclavicular joints.

Regardless of the number of symptomatic joints at disease

onset, most patients progress to additional joint involvement

in the absence of effective treatment.

Ongoing destruction of joints, as evidenced clinically by the

appearance of joint deformities & radiographically by juxta-

articular erosions, joint-space narrowing, bony ankylosis.

Arthritis mutilans the end stage of the destructive process, where

loss of bony architecture allows complete subluxation and

telescoping of the involved digit (“doigt en lorgnette” or opera-

glass finger).

This phenomenon is uncommon and is associated with longstanding,

poorly controlled disease.

Arthritis Mutilans

Dactylitis “sausage digit”

The complete swelling of a single digit of the hand or foot

A distinctive feature of the spondyloarthropathies, and it is

common in psoriatic arthritis, occurring in 30-50%

of patients at some point during the course of the disease.

Toes are more frequently involved than fingers

Enthesitis Inflammatory process occurring at the site of insertion of tendons

into bone

up to 40% of psoriatic arthritis patients.

On examination, there is a soft tissue swelling &tenderness to

palpation & may overlying erythema and warmth

Common sites for enthesitis:Achilles tendon, plantar fascia, and

pelvic bones.

Entheseal inflammation may evolve to destruction of the

adjacent bone and joints.

Skin changes All forms of psoriasis are associated with arthritis although classic psoriasis vulgaris is seen

most frequently.

Typical psoriatic lesions are erythematous plaques that produce scaling with scratching

Interestingly, many patients with psoriatic arthritis have only mild to moderate

skin disease, and there has been no consistent correlation between the degree of psoriasis and

the extent of joint involvement.

The psoriasis may be subtle so careful examination of the entire skin surface must be

performed when psoriatic arthritis is suspected

, with particular attention to the hairline, scalp, external auditory canal, periumbilical

area, and gluteal cleft As with uncomplicated psoriasis

,

Nail involvement

Common

Psoriatic nail changes include ridging, pitting,

onycholysis, and hyperkeratosis

May represent the manifestation of psoriasis before

the presence of more characteristic skin lesions.

Nail changes on the affected finger virtually always

occur when psoriaticarthritis affects a DIP joint

.

Spondyloarthropathy

Symptomatic involvement of the sacroiliac joints and

axial skeleton is less common than peripheral joints.

Sacroiliitis usually unilateral & presents with pain and

stiffness in the lower back or buttock.

Tenderness can sometimes be elicited by direct

compression teston SIJ or Gaenslen test

common site of skeletal involvement is the cervical spine.

extensive inflammation and erosion may lead to atlantoaxial

(C1–C2) instability, which can produce cervical myelopathy

as the odontoid process erodes. This process is often clinically

silent and painless. Involvement of other levels of the

spine is also seen in psoriatic arthritis with syndesmophytes,

which often arise from the midpoint of a vertebral body,

bridge adjacent vertebrae, and restrict motion of the spine.

In contrast to the continuous ascending spinal involvement

in ankylosing spondylitis, psoriatic spinal involvement is frequently

discontinuous, affecting noncontiguous vertebrae or

areas

Extraarticular manifestations

Eye disease includes conjunctivitis

in 20% and acute iritis in over 7% of cases. Iritis can be

bilateral and is more commonly associated with

axial involvement.

Other less common features include oral ulcers, urethritis,

nonspecific colitis, and rarely

dilatation of base of aortic arch causing aortic insufficiency.

Can laboratory tests help in diagnosing psoriatic

arthritis? By definition, psoriatic arthritis is classified as a “seronegative”

arthritis, meaning that the rheumatoid factor is typically negative

However, low titer rheumatoid factor can be detected in 5% to 9%

and Anti-CCP in 5% of psoriatic arthritis patients. This can make it

difficult to separate from coexistent rheumatoid arthritis

. However, the presence of DIP involvement, enthesitis, and dactylitis

supports a diagnosis of psoriatic arthritis regardless of the

serologies.

ANA are reported in 10% to 15%.

ESR , CRP and anemia may vary with disease activity

• Patients with an elevated ESR and CRP are more likely to have

polyarticular disease and a worse prognosis

Hyperuricemia is seen in 20% and related to the increased

incidence of the metabolic syndrome seen in patients with psoriatic

disease.

Analysis of synovial fluid reveals inflammatory fluid with a

neutrophilic predominance.Synovial fluid analysis reveals

inflammatory fluid, with

white blood cell counts usually in the 5000–50,000/mcL

range.

What radiographic features help to differentiate psoriatic arthritis

from other inflammatory

diseases?Overall, 45% to 50% of patients will develop erosions within the first 2 years of their

disease and eventually 67% will develop radiographic changes:

• Asymmetric involvement.

• Relative absence of juxtaarticular osteopenia.

• Involvement of DIP joints.

• Erosion of the terminal tufts (acroosteolysis).

• Whittling of the phalanges.

• Cupping of the proximal portion of the phalanges (pencil-in-cup deformity).

• Bony ankylosis distal to metacarpophalangeal (MCP) joints.

• Osteolysis of bones (arthritis mutilans).

• Polyarticular unidigit—MCP,(PIP), and DIP of same finger involved.

• Sacroiliac and spondylitic changes (usually asymmetric).

Arthritis mutilans. Severe destructive changes with multiple erosions

and “pencil-in-cup” deformities

Third left distal interphalangeal joint monoarthritis

with prominent new bone formation.

Periostitis. Radiograph of the thumb shows a marginal erosion of the

base of the distal phalanx, with extensive

cloaking of the surface of this phalanx with irregular periosteal new

bone.

Acro-osteolysis. Destruction of the tufts of the distal

phalanges of both second toes

Asymmetric right-sided sacroiliitis

MSUS is more sensitive than clinical examination in detecting subclinical

synovitis in early psoriatic arthritis

• MSUS features at the enthesis include entheseal thickening,

hypoechoic change, increased vascularity as shown

on power Doppler, tenosynovitis, and bony erosions or

enthesophyte formation

• MSUS guidance for small joint or

entheseal aspiration or injection may have particular application

in patients with psoriatic arthritis.

Right

Right plantar fascia thickening compared with the left.

Left PL fascia long

Transverse section

through the metacarpophalangeal joint showing right

tenosynovitis

Right

Extensor tenosynovitis. Longitudinal ultrasound image of

the dorsum of the wrist shows lobulated, hypoechoic thickening of the extensor tendon sheath (arrowheads)

surrounding an extensor digitorum tendon (T).

Power Doppler has been used and shows hyperaemia (red and orange pixels) in the thickened tendon sheath

Retrocalcaneal bursitis

and enthesitis. Longitudinal ultrasound image with Power Doppler shows hypoechoic thickening of the retrocalcaneal

bursa (arrows), deep to a

severely thickened distal Achilles tendon. Abnormal color flow is demonstrated in the tendon, indicating

neovascularization. There is also irregularity

of the cortex of the calcaneus at the tendon insertion caused by erosions.

MRI

• Showing enthesitis and bone marrow edema at

insertion sites of enthuses

• Sacroiliitis before X-ray changes.

Treatment

• NSAIDS

• Local steroid injection

• DMARDs “Methotrexate, sulfasalazine, leflunomide, and

cyclosporine “

• Apremilast is a tsDMARD acting as a PDE4-inhibitor and has

been demonstrated to be efficacious in PsA

Anti-TNF

”Etanercept,

Infliximab, Adalimumab, Golimumab, & Certolizumab Pegol”

1st choice as well established efficacy/safety balance in PsA

Demonstrated efficacy in PsA, for skin and joint involvement, as

well as in preventing radiographic damage

Ustekinumab is a fully human IgG1κ monoclonal antibody

that binds to the common p40 subunit shared by IL-12 and23.

Secukinumab is a fully human, high affinity,

anti-IL-17A monoclonal antibody that binds to

and neutralizes IL-17A

Both may be useful but are recommended here only as

alternatives, especially if TNFis fail or cannot be applied

EULAR

recommendations for the management

of psoriatic

arthritis with pharmacological therapies:

2015 update

Active disease: 1 or more tender and inflamed joints; tender enthesis point, dactylitic digit, and/or inflammatory

back pain;

Adverse prognostic factors; 5 active joints; radiographic damage; elevated acute phase reactants; extra-

articular manifestations, especially dactylitis.

The treatment target is clinical remission or, if remission is unlikely to be achievable, at least low disease activity;

clinical remission is the absence of signs and symptoms.

For patients with peripheral arthritis and an inadequate response to at least one csDMARD, in whom TNF

inhibitors are not appropriate. With predominant spinal involvement, active enthesitis and/or dactylitis no

csDMARD needed – use a bDMARD with preferencefor a TNFi.

bDMARD, biological DMARD

csDMARDs, conventional synthetic DMARD

tsDMARD, targeted synthetic DMARD eg such as a PDE4-inhibitor Apremilast