When to suspect a vasculitis

Primary systemic vasculitides are rare diseases affecting blood vessel walls. The type and patterns of distribution of the organs affected usually reflect the size of the vessels predominantly involved, and the patterns of clinical manifestations are generally useful to reach a specific diagnosis. However, presenting symptoms may lack adequate specificity for a prompt diagnosis, leading to a diagnostic (and therapeutic) delay, often causing irreversible damage to the affected organs. Due to their rarity and variable clinical presentation, the diagnosis of primary vasculitides could be challenging for physicians. Vasculitis mimickers, i.e. the clinical conditions that could be likely mistaken for vasculitides, need to be carefully ruled out, especially before starting the immunosuppressive therapy. We present here a practical approach to the diagnosis of primary systemic vasculitides involving large, medium and small size vessels, and reviewed most of the conditions that could mimic primary systemic vasculitides. Introduction Vasculitides are defined as inflammation of the blood vessels, often impairing the local blood circulation and leading to structural damage, tissue ischemia and necrosis.1,2 The type and patterns of distribution of the affected organs usually reflect the predominant size of the vessels involved, suggesting one or more possible diagnoses of vasculitis.3 Vasculitides may be caused by an underlying disease or occur as a primary process; in the latter case the precise pathogenic mechanisms is not yet fully understood.1,2 Because of their rarity, primary vasculitides are sometimes difficult to diagnose. In several cases, the presenting symptoms might lack adequate specificity for a prompt diagnosis, leading to a diagnostic (and, therefore, therapeutic) delay that could irreversibly damage the target organs.4-6 In this respect, exhaustive medical history collection and an extended clinical examination constitute the first step of the work-up. When possible, a biopsy of an affected organ is recommended to confirm the clinical diagnosis.7,8 On the other hand, other clinical conditions that could be likely mistaken for vasculitides need to be carefully ruled out (i.e. vasculitis mimickers), especially before starting the immunosuppressive therapy.9-12 Here we outline a practical approach to the diagnosis of vasculitis and review most of the conditions that need to be rigorously recognized, when diagnosing the most common forms of primary systemic vasculitides involving large, medium and small size vessels. When to suspect a vasculitis Given the heterogeneous spectrum of clinical manifestations, it is not possible to outline an algorithm which reflects the complete diagnostic process for patients with suspected vasculitis.13,14 However, several clues in medical history, physical examination, laboratory and imaging findings might be of help.15 Specifically, vasculitis should be considered in all patients with constitutional symptoms (fever, fatigue, weight loss and/or musculosckeletal symptoms such as arthralgia or myalgia) in combination with evidence of vessel involvement in imaging (mostly for medium-large vessel vasculitis) or clinical evidence of single and/or multiorgan dysfunction (for all vasculitis). There are classification criteria for vasculitides and a stepwise algorithm for classification of ANCA-associated vasculitis (AAV) specifically designed for epidemiological studies7,13,16-20 The Chapel Hill Consensus Conference (CHCC) nomenclature, revised in 2012, categorizes vasculitides based on the size of the most affected vessels (i.e., large, medium, and small vessel vasculitis) in order to disCorrespondence: Alvise Berti, Division of Rheumatology, Santa Chiara Hospital, Largo Medaglie D’oro, 9, 38122 Trento (TN), Italy. E-mail: alvise.berti@apss.tn. it ; alvise.berti@gmail.com