title: Persistent 5th aortic arch--a great pretender: three new covert cases.
abstract: Although persistence of the embryonic fifth aortic arch is considered a rare congenital malformation, analysis of the records of the cardiopathological collections of the Brompton and Killingbeck Hospitals reveals 6 examples in approximately 2000 specimens, an incidence amongst our material of 1 in 330. Since our review of the literature reveals only a further 13 described cases, we wonder if the condition may go unrecognized rather than being exceedingly rare. This possibility is further supported by the fact that 3 of our cases were incorrectly interpreted when initially described. In this report, we describe the details of 2 of these specimens and one other case that was not included in our earlier descriptions of this malformation. The first case had the persistent fifth arch as a conduit between the pulmonary and systemic circulations in the setting of aortic atresia with interruption of the aortic arch. The second case demonstrated a double lumen aortic arch, the fifth arch in this instance being an accessory systemic-to-systemic conduit. In the final case, the persistent arch was initially considered to represent an aorto-pulmonary window but review revealed an aortic to pulmonary conduit more in keeping with the presence of a fifth arch. We conclude that the powers of mimicry of this enigmatic structure may account for its apparent rarity.
authors.affiliation: Department of Paediatrics, Brompton Hospital, London, U.K.
authors.forename: L M
authors.initials: LM
authors.lastname: Gerlis
authors.forename: S Y
authors.initials: SY
authors.lastname: Ho
authors.forename: R H
authors.initials: RH
authors.lastname: Anderson
authors.forename: P
authors.initials: P
authors.lastname: Da Costa
mesh_terms: D001013:Aorta, Thoracic / Q000002:abnormalities*; D003937:Diagnosis, Differential; D006330:Heart Defects, Congenital / Q000175:diagnosis / Q000453:epidemiology / Q000473:pathology*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn