14
Differential Diagnosis (Table 4)
Î Cryoglobulinemia is often found in many conditions that result in
vasculitis. (D)
Î Autoinflammatory syndromes are a group of conditions that involve
aberrant activation of mediators of the innate immune response with
resultant fever and other symptoms. (C) (Table 5)
Î Cryopyrin-associated periodic syndromes (also referred to as
cryopyrinopathies) are a group of autoinflammatory syndromes that
are characterized by abnormalities in the C1AS1 gene, which encodes
for the cryopyrin protein, and are associated with an urticaria-like rash
(pseudourticaria). (C) (Table 5)
Î Hypocomplementemic or normocomplementemic urticarial vasculitis
is associated with decreased or normal complement (C1q, C4, and C3)
levels and a biopsy that reveals vasculitis of dermal blood vessels with
leukocytoclasis. (C) (Table 5)
Î Hypocomplementemic urticarial vasculitis syndrome (HUVS) is
a more severe form of this condition associated with arthralgias,
glomerulonephritis, uveitis or episcleritis, recurrent abdominal pain,
obstructive lung disease, and urticaria and/or angioedema. (C)
Î Swelling of the area in the medial portion of the upper eyes might be
a sign of thyroid orbitopathy and misinterpreted as angioedema. (C)
(Table 6)
Î Urticaria-like dermatoses can occur at various stages of pregnancy. (C)
(Table 6)
Î Women who present with cyclical urticaria can have autoimmune
progesterone-induced dermatitis. (C) (Table 6)
Î Episodic attacks of angioedema with weight gain are characteristic
of the syndrome episodic angioedema with eosinophilia (Gleich
syndrome). (C)
Î Hypereosinophilic syndrome (HES) should be considered when the
peripheral total eosinophil count exceeds 1500/mL for >6 months in
the absence of other causes of peripheral eosinophilia. (C)
Î Cutaneous mast cell disorders that can present with urticaria-like
lesions include urticaria pigmentosa (UP), mastocytomas, and
telangiectasia macularis eruptiva perstans (TMEP). (C) Mast cell
activation disorders can also present with urticaria and angioedema but
usually have additional systemic symptoms. (C) (Table 7)
Î Erythema multiforme can resemble urticaria and might be caused by
viral infections (e.g., herpes), mycoplasma infection, or medications.
(C)
Differential Diagnosis
