Incidental mastoid opacification on computed tomography in the pediatric population

Objectives: Incidental mastoid opacification (IMO) is a common radiologic finding and source of referral to otolaryngologists. Our objectives were to: 1) determine the rate of IMO in our pediatric population; 2) identify those with clinical mastoiditis; and 3) identify factors necessitating an otolaryngology consultation. Methods: This was a retrospective chart review at an academic, tertiary, pediatric hospital in an urban setting. Pediatric patients with the keyword ‘mastoid’ on a computed tomography (CT) scan report were reviewed. The effect of age, gender, season and the use of contrast media on the rate of IMO was also analyzed. Chi-square analysis was used to compare the significance of categorical frequencies. Results: The rate of IMO in our cohort was 14.2% (164/1157). In children <8 years of age, the IMO rate was 22.0% compared to 5.6% in children 8–17 years of age (p < .001). The IMO rate in male children was 16.6% compared to 11.0% in female children (p = .007). There was no statistically significant higher rate of IMO during winter (15.1%) compared to summer (9.0%) and in CT scans with contrast (16.0%) compared to without contrast (14.0%). Our department of otolaryngology was formally consulted in 3% (5/164) of IMO cases. None of those patients had clinical mastoiditis. Conclusions: This is the largest study identifying IMO on CT and in children to date. Although the overall rate of IMO in the pediatric population is 14.2%, it is rarely clinically significant.