<unk>  <unk> , formerly known as<unk><unk>  systemic<unk> , is a chronic inflammatory condition characterized by tissue infiltration with lymphocytes and<unk> -secreting plasma cells, various degrees of fibrosis (scarring) and a usually prompt response to oral steroids. In approximately 51–70% of people with this<unk> , serum<unk>  concentrations are elevated during an acute phase. It is a relapsing-remitting<unk>  associated with a tendency to mass forming, tissue-destructive lesions in multiple sites, with a characteristic histopathological appearance in whichever site is involved. Inflammation and the deposition of connective tissue in affected anatomical sites can lead to organ dysfunction, organ failure, or even death if not treated. Early detection is important to avoid organ damage and potentially serious complications. Treatment is recommended in all symptomatic cases of<unk>  and also in asymptomatic<unk>  involving certain anatomical sites.
IgG4-related disease
IgG4-related skin disease
Anti-IgLON5 disease
IgA vasculitis
Isolated primary immunoglobulin M deficiency
Antisynthetase syndrome
Undifferentiated connective tissue disease
Leukotriene receptor antagonist-associated Churg–Strauss syndrome