The FP suspected psoriatic arthritis (PsA) based on the silvery plaques on the dorsum of her hand and the swelling of her distal interphalangeal joints. The patient also had silvery plaques on her elbows and some pitting of the nails. Lab tests confirmed the FP’s suspicion: The patient had an elevated ESR that was consistent with an inflammatory process (rather than the degenerative changes of osteoarthritis [OA]). In addition, radiographs showed periarticular joint erosions typical of PsA.
Changes of PsA on x-rays may show periarticular joint erosions, “pencil-in-cup” deformity, osteolysis, telescoping of digits, and asymmetric sacroiliitis. The distribution of PsA can involve the hands, feet, knees, spine, and sacroiliac joints. There are 5 types of PsA:
- Symmetric arthritis involves multiple pairs of symmetric joints in the hands and feet. It resembles rheumatoid arthritis.
- Asymmetric arthritis involves one to 3 joints (eg, knee, hip, ankle, or wrist) in an asymmetric pattern. Hands and feet may have enlarged “sausage” digits due to dactylitis. It is the most common type of PsA.
- Distal interphalangeal predominant (DIP) arthritis involves distal joints of the fingers and toes. It may be confused with OA, but nail changes (eg, pitting) are common in this type of PsA.
- Spondylitis (axial arthritis) includes inflammation of the spinal column that causes a stiff neck and pain in the lower back and sacroiliac area. The arthritis may involve peripheral joints in the hands, arms, hips, legs, or feet.
- Arthritis mutilans is a severe, deforming type of arthritis that usually affects a few joints in the hands and feet.
Treatment options include methotrexate and biologic anti-tumor necrosis factor-α medications. In this case, the patient was referred to a rheumatologist and chose to begin a low dose of oral methotrexate weekly.
Photo and text for Photo Rounds Friday courtesy of Richard P. Usatine, MD. This case was adapted from: Chumley H, Usatine R. Arthritis overview. In: Usatine R, Smith M, Mayeaux EJ, et al, eds. Color Atlas of Family Medicine. 2nd ed. New York, NY: McGraw-Hill; 2013:562-568.
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