Patterns of Sonographically Detectable Echogenic Foci in Pediatric Thyroid Carcinoma with Corresponding Histopathology: An Observational Study.

BACKGROUND AND PURPOSE

Small echogenic foci within pediatric thyroid nodules are commonly seen by ultrasound and are one of the features used to determine the level of suspicion for malignancy. These are sometimes termed "microcalcifications," but their relation with malignancy is controversial due to the lack of standard terminology. Our aim was to evaluate sonographic patterns of echogenic foci in malignant pediatric thyroid nodules and describe the distribution of corresponding psammoma bodies and other histopathologic findings in thyroidectomy specimens.

MATERIALS AND METHODS

Ultrasounds of 15 pathologically proved malignant thyroid nodules in children were retrospectively reviewed by 2 radiologists who separately classified echogenic foci into the 4 morphologic patterns described in the American College of Radiology Thyroid Imaging, Reporting and Data System and noted their presence and distribution. Interobserver agreement was assessed, and consensus was reached for nodules for which there was disagreement. Surgical pathology findings from thyroidectomy specimens were retrospectively reviewed for the presence and distribution of psammomatous and dystrophic/stromal calcifications and eosinophilic/sticky colloid. Ultrasound and histopathologic ratings were compared, and frequencies and percentages corresponding to observed agreement levels were calculated.

RESULTS

Interobserver agreement between radiologists' sonographic assessments for the presence and distribution of echogenic foci ranged from 53% to 100% for all categories. Punctate echogenic foci were present in all nodules, and macrocalcifications, in 27%. Histopathology of the 15 nodules revealed that only 4 (27%) had psammomatous calcifications, while 9 (60%) had stromal calcifications and 8 (53%) had sticky colloid.

CONCLUSIONS

Sonographically detectable echogenic foci in malignant pediatric thyroid nodules can be reliably classified on the basis of American College of Radiology Thyroid Imaging, Reporting and Data System, with punctate echogenic foci composing the most common subtype. These echogenic foci do not represent psammomatous calcifications most of the time; instead, more than half of the malignant thyroid nodules with echogenic foci contained stromal calcifications or sticky colloid.