Inflammatory myopathies overlapping with systemic sclerosis: a systematic review

We performed a systematic review of the clinical manifestations and complementary exams of patients with myopathies and systemic sclerosis overlap syndrome (MyoSScOS). Systematic review from January 1976 to November 2021 according PRISMA protocol on three electronic databases: PubMed, Web of Science, and Scopus. Studies were analyzed based on the following eligibility criteria: at least one combination of the terms described in the search strategy appears in the title; written in English, Portuguese, or Spanish; and addresses MyoSScOS. Brief communications, reviews, studies that addressed myopathies in children, congress proceedings, monographs, and dissertations were excluded. Thirty-five articles were selected. MyoSScOS seems to be more common in women. It also commonly affects the esophagus and joints with symmetrical and bilateral muscle involvement, Raynaud's phenomenon, and impairment of forced vital capacity. Concerning SSc, the most common subtype was the diffuse form. Cardiovascular and pulmonary complications are an important cause of death. Anti-centromere, anti-PM/Scl, anti-Scl70, anti-RNA polymerase III, anti-Ku, and anti-RNP were more correlated with this entity, and muscle biopsies may present a more aggressive pattern. Electroneuromyography patterns are quite similar to those found in inflammatory myopathies. The absence of studies with robust methodologies and the large number of case reports and series make more robust statistical analyses such as meta-analyses unfeasible. The characterization of MyoSScOS is important for the formulation of therapeutic measures and specific treatments aiming at better quality of life and prognosis. Greater and better theoretical contributions are necessary to better characterize it.