Classification and Disease Subsets in Clinical Practice

Systemic sclerosis (SSc) manifests with a heterogeneous array of immunologic, fibrotic, and vasculopathic features and lacks a single diagnostic test. The diagnosis is based on the physician's expertise and judgment. Classification criteria are used to distinguish individuals with SSc from other conditions so homogeneous groups of patients are included in studies. Classification criteria are also used to identify subsets of SSc. This chapter discusses the evolving concepts of diagnosis and classification in SSc.