The prevalence and anatomy of the pyramidal lobe of the thyroid gland: A meta-analysis with implications for thyroid surgery.

The pyramidal lobe (PL), also known as the third lobe of the thyroid gland or lobe of Lalouette is an embryological remnant of the caudal end of the thyroglossal tract. The following meta-analysis aims to provide a detailed analysis of the anatomical variations of the PL using the available data in the literature. Major online medical databases such as PubMed, Scopus, Embase, Web of Science, Cochrane Library, and Google Scholar were searched in order to find all studies considering the prevalence and anatomy of the PL of the thyroid gland. Finally, a total of 24 studies that met the required criteria and contained complete and relevant data were included in the present meta-analysis. The pooled prevalence of the PL was found to be 42.82% (95% CI: 35.90%-49.89%). An analysis showed that the mean length was 23.09 mm (SE: 0.56). The mean width was found to be 10.59 mm (SE: 0.77). The pooled prevalence of the PL originating from the left lobe (LL) was established at 40.10% (95% CI: 28.83%-51.92%). In conclusion, we believe that this is the most accurate and up-to-date study regarding the complete surgical anatomy of the PL. The PL was prevalent in 42.82% of the cases, being slightly more prevalent in males (40.35%) than females (37.43%). The mean length and width of the PL were 23.09 mm and 10.59 mm, respectively. Our results should be taken into consideration when performing procedures on the thyroid gland, such as thyroidectomies. The presence of the PL can affect the completeness of this procedure and lead to postoperative complications.