Introduction Joint involvement in systemic sclerosis (SSc) was first described by Forget in 1847.1Rodnan studied a series of 150 cases with SSc and noted that 41% had arthritis and arthralgia within 1 year of onset of Raynaud's phenomenon (RP) and/or cutaneous signs.2Some of the x-ray findings of SSc include soft tissue atrophy, loss of joint space, osteoporosis, calcinosis, and acro-osteolysis. Although rare, erosive arthritis has been noted in the past. We observed three patients with erosive joint manifestations involving different joints in SSc.
Case Reports Case 1: A 47-year-old female with a history of sclerodactyly, RP, polyarthralgias, dysphagia, GERD, and pulmonary hypertension. Physical examination (PE) was consistent with (c/w) diffuse sclerosis, calcinosis over the elbows, hyperpigmentation, digital ulcers, tapering of the digits, and diminished range of motion of the wrists and elbows. Laboratory testing (LT) revealed a positive anti-SSA and anti-Scl 70 antibodies, weakly positive rheumatoid factor (RF), and negative RNP/SM and ANA antibodies. Radiographs showed erosions of IP, MCPs, MTPs, and radioulnar joint, along with the acro-osteolysis of the hand and calcinosis of the right thumb and right third digit. Case 2: A 31-year-old female with a history of RP, dysphagia, GERD, sclerosis, and polyarthralgias. PE was c/w sclerodactyly, flexion contractures (FC) of the PIPs and DIPs, diffuse sclerosis, and digital ulcers. LT revealed positive anti-Scl-70 antibody and negative RF, ANA, and RNP/SM antibodies. MRI of the left knee showed diffuse synovial proliferation, tendinosis, and periarticular osseous erosions of the tibia. Hand radiograph was c/w narrowing of the carpal bones. Case 3: A 48-year-old female with a history of RP, ILD, polyarthralgia, and polyarthritis. PE was c/w sclerodactyly and telescoping of the digits, FC and calcinosis of elbows, and FC of the knees and wrists. LT revealed positive anti-Scl-70 antibody and negative RF and RNP/SM antibody. X-ray findings showed erosions of the distal end of the humerus and tapering of the ulna and extensive calcinosis of the wrists, elbows, and knees.
Discussion Ninety percent of the patients with SSc present with articular findings. Acro-osteolysis is the most common x-ray finding in SSc. Rabinowitz et al reviewed the x-ray findings of 24 patients with SSc; bone erosions were seen in 13 patients.3In the above cases, erosive arthritis involved the small joints of the hand, wrist, elbows, and knees, simulating rheumatoid arthritis (RA). Only one of three patients had a weakly positive RF, but none had a history or physical examination findings suggestive of RA. Two patients had erosive changes involving the IP, MCPs, and distal radioulnar and carpal bones. One patient had minimum erosions in the hand and extensive erosions of the knees on MRI. We propose that these patients represent a unique population of SSc patients in that they have erosive changes quite distinctive of SSc.