Table 3 Differential diagnosis

Immunological disorders

Adult-onset Still’s disease (AOSD)

Systemic lupus erythematosus (SLE)

Acquired C1 esterase deficiency

Hematological disorders

Monoclonal gammopathy of unknown significance (MGUS)

Polyneuropathy, organomegaly, endocrinopathy, monoclonal gammopathy, and skin changes (POEMS) syndrome

Waldenström’s macroglobulinemia (WM)

Lymphoma, other than WM

Multiple myeloma

Hereditary auto-inflammatory syndromes

Cryopyrin-associated periodic syndrome (CAPS)

Infectious diseases

Hepatitis B, C

Chronic meningococcemia

Other

Chronic spontaneous urticaria

(Hypocomplementaemic) urticarial vasculitis

Delayed pressure urticaria

Cryoglobulinemia

Erdheim-Chester disease

Mastocytosis