An unusual urticarial eruption: Familial cold autoinflammatory syndrome

This is a case of a 26-year-old Caucasian woman with a lifelong history of an episodic urticaria associated with arthralgia, precipitated by exposure to cold. She had no other significant past medical history. She reported several family members with a history of very similar episodic eruptions without definitive diagnoses. An examination showed an urticarial eruption over her limbs with no other systemic findings. A baseline full blood examination, serology and autoimmune screen were normal. A skin biopsy was consistent with urticaria, with dermal oedema and a perivascular infiltrate. Following genetic testing, she was found to be heterozygous for a mutation, p.Ala439Val in the NLRP3 gene, known to cause familial cold autoinflammatory syndrome (FCAS), which typically presents with urticaria, conjunctivitis and arthralgia, as described in this patient. FCAS is one subtype of a group of conditions known as cryopyrin-associated periodic syndromes (CAPS). CAPS are rare, autosomal dominant inherited conditions with a spectrum of phenotypes, characterised by increased interleukin-1β release with subsequent local and systemic proinflammatory and pyrogenic effects.