1. Scleroderma (SSc): We use the ACR/EULAR criteria for the diagnosis and classification of systemic sclerosis. Patients with SSc-APAH may exhibit features of limited scleroderma, such as, calcinosis, Reynaud's, esophageal dysmotility, sclerodactyly (with skin thickening of the fingers of both hands extending proximal to the metacarpophalangeal joints) and telangiectasia. In those with limited scleroderma anticentromere antibodies are commonly positive. In patients with diffuse cutaneous scleroderma, SSc-PAH can also be seen. They exhibit diffuse skin thickening and tightening. Anti-topoisomerase antibodies (anti Scl70) may be positive but interestingly, their absence is more likely to be associated with PAH. Other autoantibodies that are associated with an increased risk of SSc-PAH include anti-U1-ribonucleoprotein antibodies (RNP), nucleolar pattern of anti-nuclear antibody (nucleolar-ANA), and rarely antiphospholipid antibodies.