Clinical characteristics of sarcoidosis patients with systemic sclerosis-specific autoantibody: Possible involvement of thymus and activation-regulated chemokine and a review of the published works

Sarcoidosis and systemic sclerosis (SSc) are both multisystem disorders of unknown etiology. Some cases having both sarcoidosis and SSc have been reported previously. The present study was to investigate clinical features in sarcoidosis patients who possessed SSc-specific autoantibody. The pathophysiology of each disease, including shared pathways leading to the development of both conditions, is reviewed in addition to previous reports of patients with concomitant SSc and sarcoidosis. SSc-specific autoantibodies including anticentromere antibody (ACA), anti-topoisomerase I antibody, anti-RNA polymerase III antibody and anti-U1RNP antibody were examined in sarcoidosis patients. Complete medical histories, clinical examinations and laboratory tests were conducted for all patients. For reviewing previously published reports, all cases were retrieved through a PubMed search. ACA was most frequently observed in sarcoidosis patients. Plaques and papules were the most frequent as the cutaneous sarcoidosis lesions. Soluble interleukin-2 receptor was elevated in most of the cases (6/ 8, 75%), and thymus and activation-regulated chemokine (TARC) was elevated in all cases (6/ 6, 100%). Together with our two cases (cases 1 and 3), a review of previously reported cases of sarcoidosis patients concomitant with SSc showed high frequency of ACA and plaques as cutaneous lesions. We suppose that TARC may play some roles in the production of SSc-specific autoantibodies and development of concomitance with SSc in sarcoidosis, although the mechanisms remain unknown.