Age / Sex : 28 / F

Chief complaint :

Erythematous painful swelling on Lt. 4th finger, scaly silvery erythematous plaque on whole body


What is your diagnosis?

Two weeks later, you can see the final diagonosis with a brief discussion of this case (Please submit only one answer).


Courtesy : 강우영, Kang Woo Young, 고려대학교 구로병원, Korea University Guro Hospital

Psoriatic arthritis

Discussion

Findings:

HAND PA and oblique radiograph shows soft tissue swelling, lack of osteoporosis, joint space narrowing, bony erosion, adjacent irregular bony proliferation and periostitis at 4^th DIP joint of left hand.

Differential Diagnosis:

Other seronegative spondyloarthropathies (AS, reactive arthritis)

Rheumatoid arthritis

Erosive osteoarthritis

Discussion:

Psoriatic arthritis is an inflammatory arthritis that occurs in 10 to 15% of people with psoriasis. Although arthritis can coincide or antedate skin disease, the characteristic rash commonly precedes joint disease by months or years. Histocompatibility typing in patients with psoriatic arthritis has revealed a 25 to 60% incidence of HLA-B27 antigen.

Psoriatic arthritis can affect synovial and cartilaginous joints and sites of tendon and ligament attachment to bone in both the appendicular and the axial skeleton. The most typical sites of abnormality are the interphalangeal joints of the hands and foot, MCP and MTP joint, calcaneus, sacroiliac joint, and spine.

The characteristics radiographic findings of psoriatic arthritis are:

 . Enthesitis

. Bony erosion: “mouse–ear” (marginal bone erosions with adjacent irregular bone proliferation), "pencil-in-cup" deformities (protrusion of a blunted and distorted osseous surface into an adjacent expanded one)

 . Periostitis

. Joint subluxation or interphalangeal ankylosis

. Arthritis mutilans

. Ivory phalanx involving the distal phalanx of the great toe

. Sacroiliitis: often asymmetrical

. Spondylitis: asymmetric paravertebral ossifications and relative sparing of the facet joints

References:

Resnick, Bone and Joint Imaging, 3rd edition.

Jacobson JA, Girish G, Jiang Y, Resnick D. Radiographic evaluation of arthritis: inflammatory conditions. Radiology. 2008 Aug;248(2):378-89.

Klecker RJ, Weissman BN. Imaging features of psoriatic arthritis and Reiter’s syndrome. Semin Musculoskelet Radiol. 2003 Jun;7(2):115-26.