INTRODUCTIONOssification of the cricoid ridge mimicking impacted upper aerodigestive tract fish bone has been described in several case reports. We performed this study to determine the prevalence of such ossification in an adult population from Singapore and to identify specific imaging features that may aid in differentiating patients with cricoid ridge ossification from those with an upper aerodigestive tract impacted fish bone.

METHODSWe retrospectively evaluated 442 lateral neck radiographs of patients aged 16 years and above that were taken at the adult emergency department at National University Hospital, Singapore, during the four-month period between 1 September 2014 and 31 December 2014.

RESULTSOssification of the cricoid ridge mimicking fish bone appeared in 3.2% of our adult patients and was more common among patients aged above 40 years (n = 11/227; 4.8%). The ossified cricoid ridge was usually located at the C6 level (n = 9) and had a mean length of 5.5 (range 2-9) mm.

CONCLUSIONOssified cricoid ridges may be misinterpreted on lateral neck radiography as ingested fish bones. While ossification of the cricoid ridge mimicking fish bones is rare, awareness of such ossification would reduce unnecessary further investigations of the upper aerodigestive tract in patients suspected of having an impacted foreign body.