Psoriasis is a commonly encountered systemic condition, usually presenting with chronic erythematous plaques with an overlying silvery white scale. 1 Extracutaneous manifestations, such as joint or spine (axial) involvement, can occur along with this skin disorder. Psoriatic arthritis (PsA) is a chronic, heterogeneous disorder characterized by inflammatory arthritis in patients with psoriasis. 2,3 Until recently treatment of PsA has been limited to a few medications.
Continuing investigations into the pathogenesis of PsA have revealed new treatment options, targeting molecules at the cellular level. Over the past few years, additional medications have been approved, giving providers more options in treating patients with psoriasis and PsA. Furthermore, a multidisciplinary approach by both rheumatologists and dermatologists in evaluating and managing patients at VA clinics has helped optimize care of these patients by providing timely evaluation and treatment at the same visit.
Psoriasis Presentation and Diagnosis
Genetic predisposition and certain environmental factors (trauma, infection, medications) are known to trigger psoriasis, which can present in many forms. 4 Chronic plaque psoriasis, or psoriasis vulgaris, is the most common skin pattern with a classic presentation of sharply demarcated erythematous plaques with overlying silver scale. 4 It affects the scalp, lower back, umbilicus, genitals, and extensor surfaces of the elbows and knees. Guttate psoriasis is recognized by its multiple small papules and plaques in a droplike pattern. Pustular psoriasis usually presents with widespread pustules. On the other hand, erythrodermic psoriasis manifests as diffuse erythema involving multiple skin areas. 4 Erythematous psoriatic plaques, which are predominantly in the intertriginous areas or skin folds (inguinal, perineal, genital, intergluteal, axillary, or inframammary), are known as inverse psoriasis.
A psoriasis diagnosis is made by taking a history and a physical examination. Rarely, a skin biopsy of the lesions will be required for an atypical presentation. The course of the disease is unpredictable, variable, and dependent on the type of psoriasis. Psoriasis vulgaris is a chronic condition, whereas guttate psoriasis is often self-limited. 4 A poorer prognosis is seen in patients with erythrodermic and generalized pustular psoriasis. 4
Psoriatic Arthritis Presentation, Classification, and Diagnosis
Prevalence of PsA is not known, but it is estimated to be from 0.3% to 1% of the U.S. population. In the psoriasis population, PsA is reported to range from 7% to 42%, 3 although more recently, these numbers have been found to be in the 15% to 25% range (unpublished observations). This type of inflammatory arthritis can develop at any age but usually is seen between the ages of 30 and 50 years, with men being affected equally or a little more than are women. 3 Clinical symptoms usually include pain and stiffness of affected joints, > 30 minutes of morning stiffness, and fatigue.
The presentation of joint involvement can vary widely. Five subtypes of arthritis were identified by Moll and Wright in 1973, which included arthritis with predominant distal interphalangeal involvement, arthritis mutilans, symmetric polyarthritis (> 5 joints), asymmetric oligoarthritis (1-4 joints), and predominant spondylitis (axial). 5 Patients with PsA may also have evidence of spondylitis (inflammation of vertebra) or sacroiliitis (inflammation of the sacroiliac joints) with back pain > 3 months, hip or buttock pain, nighttime pain, or pain that improves with activity but worsens with rest.6 The cervical spine is more frequently involved than is the lumbar spine in patients with PsA. 3