Table 1 Conditions to consider in the differential diagnosis of urticaria

Urticarial vasculitis

• Lesions are usually painful (rather than pruritic), last > 48 h, and leave discoloration on the skin

Systemic mastocytosis

•Rare condition that involves the internal organs (liver, spleen, lymph nodes, bone marrow), in addition to the skin

Atopic dermatitis

•Chronic, highly pruritic inflammatory skin disease

•Clinical manifestations vary with age

Bullous pemphigoid

•Chronic, autoimmune, blistering skin disease

Erythema multiforme

•Acute, self-limited, skin condition

•Considered to be a type IV hypersensitivity reaction to certain infections, medications, and other various triggers

Familial cold autoinflammatory syndrome

•Rare, inherited inflammatory disorder characterized by recurrent episodes of rash, fever/chills, joint pain, and other signs/symptoms of systemic inflammation triggered by exposure to cooling temperatures

•Onset usually occurs during infancy and early childhood and persists throughout the patient’s life

Fixed drug eruptions

•Lesions occur from exposure to a particular medication and occur at the same site upon re-exposure to the offending medication

•Lesions usually blister and leave residual pigmentation

Subacute cutaneous lupus erythematosus

•A non-scarring, photosensitive skin condition

•May occur in patients with systemic lupus erythematosus (SLE) and Sjögren syndrome

Pruritic urticarial papules and plaques of pregnancy

•Benign skin condition that usually arises late in the third trimester of a first pregnancy

Muckle–Wells syndrome

•Rare genetic disease that causes hearing loss and recurrent hives

•May lead to amyloidosis

Schnitzler’s syndrome with monoclonal IgG kappa gammopathy

•Rare disease characterized by chronic, non-pruritic hives, periodic fever, bone and joint pain, swollen lymph glands and an enlarged spleen and liver