What is the laboratory finding associated with diffuse scleroderma?

Diffuse scleroderma is characterized by widespread skin involvement and rapid progression of disease, including internal organ involvement. The presence of anti-Scl-70 antibodies, also known as anti-topoisomerase I antibodies, is a hallmark laboratory finding associated with diffuse scleroderma.

Anti-Scl-70 antibodies target the enzyme topoisomerase I, which plays a crucial role in DNA replication and repair. These antibodies are found in approximately 30-70% of patients with diffuse scleroderma and are linked to a poorer prognosis due to the more aggressive nature of this form of the disease. In contrast to limited scleroderma, which is associated with anti-centromere antibodies, diffuse scleroderma often presents early with multi-organ involvement.

Other antibody profiles mentioned relate to different conditions or subsets of autoimmune disorders and are not typical of diffuse scleroderma. For example, anti-centromere antibodies are primarily associated with limited scleroderma. Anti-Ro/SSA and anti-LA/SSB antibodies are associated with Sjögren's syndrome and lupus, not scleroderma. Thus, the identification of anti-Scl-70 antibodies is critical for diagnosing diffuse scleroderma and understanding its clinical implications