Systemic Sclerosis
Systemic sclerosis (SSc) is a chronic, multisystem, heterogeneous autoimmune disease. Individuals with SSc have a mortality rate approximately 2.8 times that of the general population. In the United States, the incidence is approximately 15 cases per 100,000 person-years.
The disease is characterized by inflammation, vasculopathy, and progressive fibrosis of the skin and internal organs.
SSc is frequently referred to as scleroderma; however, scleroderma includes SSc and localized forms of scleroderma that affect only the skin.
The 2 main types of SSc are defined according to the pattern of skin involvement:
limited cutaneous SSc (lcSSc) and diffuse cutaneous SSc (dcSSc).
In lcSSc, skin thickening is present distal to the elbows and knees, and facial skin thickening may or may not be present.
In contrast, dcSSc is characterized by thickening of the skin of the whole extremity, as well as that of the anterior chest, abdomen, and back, with or without facial skin involvement.
Multiple organs, including the heart, lungs, gastrointestinal tract, and kidneys, can be affected in both forms, though organ involvement is generally less severe in lcSSc.
CREST syndrome (calcinosis, Raynaud phenomenon, esophageal dysmotility, sclerodactyly, and telangiectasia) occurs frequently in lcSSC but can also occur in longstanding dcSSc.
Of patients with SSc, approximately 55% have lcSSc and 35% have dcSSc. The remaining 10% of patients with SSc have sine scleroderma or an overlap syndrome.
Sine scleroderma is a form of SSc that has characteristic clinical features but spares the skin. Overlap syndromes occur when features of another autoimmune disease are present along with SSc.
Early treatment of SSc can improve outcomes, so prompt diagnosis is important. However, diagnosis can be challenging because many patients present with nonspecific symptoms such as Raynaud phenomenon, gastroesophageal reflux, puffy fingers, and fatigue.
In addition, patients with other autoimmune disorders may present with symptoms suggestive of SSc. Testing for autoantibodies that are associated with SSc assists diagnosis and can help predict organ involvement and severity of disease.
References:
Lee YH. Overall and sex- and disease subtype-specific mortality in patients with systemic sclerosis: an updated meta-analysis. Z Rheumatol. 2019;78(2):195-201. doi:10.1007/s00393-018-0492-8
Fan Y, Bender S, Shi W, et al. Incidence and prevalence of systemic sclerosis and systemic sclerosis with interstitial lung disease in the United States. J Manag Care Spec Pharm. 2020;26(12):1539-1547. doi:10.18553/jmcp.2020.20136
Lee JJ, Pope JE. Diagnosis and management of systemic sclerosis: a practical approach. Drugs. 2016;76(2):203-213. doi:10.1007/s40265-015-0491-x
Young A, Khanna D. Systemic sclerosis: commonly asked questions by rheumatologists. J Clin Rheumatol. 2015;21(3):149-155. doi:10.1097/RHU.0000000000000232
Denton CP, Khanna D. Systemic sclerosis. Lancet. 2017;390(10103):1685-1699. doi:10.1016/s0140-6736(17)30933-9
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Biomarkers included in this panel:
CENP-A stands for centromere proteins A. Centromere antibodies can be directed against a number of centromere proteins (CENP), including CENP-A, -B, and -C, though CENP-B is thought to be the main target. These antibodies are found in 20% to 40
Learn moreCENP-B stands for centromere proteins B. Centromere antibodies can be directed against a number of centromere proteins (CENP), including CENP-A, -B, and -C, though CENP-B is thought to be the main target. These antibodies are found in 20% to 40
Learn moreU3-RNP antibodies target the U3 small nucleolar ribonucleoprotein (U3-RNP) complex, which consists of the protein fibrillarin and U3 RNA. These antibodies are found in about 4% to 10% of patients with SSc, and are especially common in African America
Learn morePM/Scl antibodies target the PM/Scl exosome complex, and most reactivity is against 2 proteins, PM/Scl-75 and PM/Scl-100. They are present in 2% to 11% of SSc patients and are associated with SSc-myositis overlap syndrome and lcSSc. PM/Scl antib
Learn morePM/Scl antibodies target the PM/Scl exosome complex, and most reactivity is against 2 proteins, PM/Scl-75 and PM/Scl-100. They are present in 2% to 11% of SSc patients and are associated with SSc-myositis overlap syndrome and lcSSc. PM/Scl antib
Learn moreRNA polymerase III antibodies target RNA polymerase epitopes 11 and 155 and are thus also known as anti-RP11 and anti-RP155. These antibodies are found in 7% to 41% of patients with SSc and occur most often in dcSSc. They are diagnostic for SSc
Learn moreRNA polymerase III antibodies target RNA polymerase epitopes 11 and 155 and are thus also known as anti-RP11 and anti-RP155. These antibodies are found in 7% to 41% of patients with SSc and occur most often in dcSSc. They are diagnostic for SSc
Learn moreScl-70 is also known as Topoisomerase I Antibody. Topoisomerase I antibodies were initially named Scl-70 based on immunoblot detection of a 70-kDa protein. The prevalence of Scl-70 antibodies in SSc varies widely across geographies and ethnicit
Learn moreScl-70 is also known as Topoisomerase I Antibody. Topoisomerase I antibodies were initially named Scl-70 based on immunoblot detection of a 70-kDa protein. The prevalence of Scl-70 antibodies in SSc varies widely across geographies and ethnicit
Learn moreThe SCL-70 antibody test is a blood test used to detect antibodies against topoisomerase I, an enzyme found in the nucleus of cells. These antibodies are part of the antinuclear antibody (ANA) family and are often associated with certain autoimmune c
Learn moreTh/To antibodies target RNase P and mitochondrial RNase ribonucleoprotein complexes. These antibodies are found in 2% to 5% of SSc patients and are primarily associated with lcSSc. Th/To antibodies are rarely found in other autoimmune diseases but ca
Learn moreU1-snRNP antibodies, also referred to as U1-RNP and Smith (Sm)/RNP, target 3 components of the U1 small nuclear ribonucleoprotein complex: U1-snRNP RNP A, U1-snRNP RNP C, and U1-snRNP RNP-70kd. These antibodies, found in 2% to 14% of SSc patients,
Learn moreU1-snRNP antibodies, also referred to as U1-RNP and Smith (Sm)/RNP, target 3 components of the U1 small nuclear ribonucleoprotein complex: U1-snRNP RNP A, U1-snRNP RNP C, and U1-snRNP RNP-70kd. These antibodies, found in 2% to 14% of SSc patients,
Learn moreU1-snRNP antibodies, also referred to as U1-RNP and Smith (Sm)/RNP, target 3 components of the U1 small nuclear ribonucleoprotein complex: U1-snRNP RNP A, U1-snRNP RNP C, and U1-snRNP RNP-70kd. These antibodies, found in 2% to 14% of SSc patients,
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