Pyramidal Lobe Prevalence, Preoperative Detection and Clinical Importance: A Literature Review

Abstract

The pyramidal lobe is an important feature of thyroid gland anatomy that is often neglected in preoperative imaging and thyroid surgery. The aim of this review is to assess the frequency of the pyramidal lobe as well as its clinical importance. The search was conducted using the Medline database (1946 to February 2020). The key words of our search were “thyroid pyramidal lobe”. The inclusion criteria specified the availability of abstracts or full-text articles in English. Out of 101 search results, 50 articles were relevant and were included in this study. The prevalence of the pyramidal lobe in recent surgical and cadaveric studies varies between 12% – 65%. Identification rates in preoperative imaging are insufficient (ultrasonography accuracy: 80.3% – 83.7%, computed tomography accuracy: 92.6%). Ultrasonography appears less diagnostically accurate (accuracy: 82.1% – 87.5%) compared to computed tomography. The pyramidal lobe is commonly involved in thyroid pathology, especially in cancer and diffuse thyroid diseases, like Graves’ disease and multinodular goiter. The pyramidal lobe is a normal component of thyroid anatomy. Intraoperative pyramidal lobe identification and resection is mandatory, in order to prevent disease recurrence.