The relationship between ultrasound microcalcifications and psammoma bodies in thyroid tumours: a single-institution retrospective study

To investigate the diagnostic accuracy of ultrasound microcalcifications for the detection of malignancy in thyroid nodules and determine the validity of the concept that ultrasound microcalcification reflects the presence of psammoma body calcification in thyroid nodules.The laboratory information system at University Hospital Galway, a tertiary referral hospital, was used to compile a list of patients who underwent thyroid lobectomy or complete thyroidectomy over a continuous 12-month period with both preoperative ultrasound and postoperative histology available (n=106) from January to December 2019. The haematoxylin and eosin-stained histology slides of each case were sourced and reviewed under light microscopy by a histopathologist to determine the presence of psammoma body calcification within both benign and malignant thyroid nodules. Two radiologists reviewed preoperative thyroid ultrasound images of each case independently and blindly, and reported on the presence of ultrasonographic microcalcification.There was a strong and significant relationship between the presence of preoperative ultrasound microcalcification and thyroid malignancy (p<0.001). Ultrasound microcalcification had a high specificity (93%) and positive predictive value (75%) for thyroid malignancy, with a diagnostic accuracy of 76%. Negative predictive value was high at 76.7%, while sensitivity was low at 42.8%. There was a strong and significant association between the presence of preoperative ultrasound microcalcification in thyroid nodules and the presence of pathological psammoma bodies on histology (p<0.001).Ultrasound microcalcification has a strong and significant association with malignancy in thyroid nodules. This study supported the theory that ultrasound microcalcification occurs secondary to the presence of psammoma bodies within thyroid nodules.