Well-demarcated symmetrical scaly plaques and dactylitis are consistent with psoriasis and psoriatic arthritis (PsA). Even in the absence of significant skin disease, a patient like this should be evaluated by Rheumatology for initiation of disease-modifying antirheumatic drugs (DMARDs).
Psoriatic arthritis manifests as a peripheral arthritis affecting the small joints of the wrists and hands, pain at the insertion of tendons and ligaments (enthesitis), or as axial arthritis. This variable presentation and the lack of specific serological marker can make diagnosis challenging. Associated symptoms beyond the musculoskeletal system include uveitis, inflammatory bowel disease, and cutaneous psoriasis.1 In contrast to osteoarthritis, PsA symptoms are often worse in the morning and improve over the course of the day. Patients with a history of psoriasis on the skin have about a 10% chance of developing PsA, with increased rates in patients who have more widespread plaques and patients with psoriasis at a young age.2 Although not pathognomonic for PsA, pitting of the fingernails may reflect episodic enthesitis in the extensor tendons of the fingers.3 Radiographs of the hands in severe cases may demonstrate narrowing of the proximal portion of the distal or proximal interphalangeal joints with a cup-like concavity of the distal half of the joint.
Conventional DMARDs (such as methotrexate and azathioprine) and biologic DMARDs (including TNF-alpha inhibitors, IL-17 inhibitors, IL-23 inhibitors) are first-line treatments and can stop or slow the progression of disease but will not reverse existing damage. For this reason, it is important to promptly start DMARD therapy after the diagnosis has been established.4
This patient was initiated on adalimumab 40 mg subcutaneously every other week. Her pain improved after 2 months of therapy and her skin plaques almost entirely resolved at 6 months.
Photos and text for Photo Rounds Friday courtesy of Jonathan Karnes, MD (copyright retained). Dr. Karnes is the medical director of MDFMR Dermatology Services, Augusta, ME.