The incidence and morphological features of pyramidal lobe on thyroid ultrasound

Abstract

The aim of this article is to document the incidence and appearances of the pyramidal lobe of the thyroid gland, and discuss the clinical relevance of this entity in sonographic practice. A prospective study was undertaken over a period of 10 months. A total of 416 consecutive patients attending head and neck ultrasound lists were scanned by a single experienced radiologist or an advanced practitioner sonographer. At the time of reporting, the presence of a pyramidal lobe was recorded. The anatomical morphology was classified into five subgroups devised for the purposes of the study. Appearances were documented in both normal and pathological glands. Of the total number of patients scanned, 90 patients were found to have pyramidal lobes, giving an overall incidence of 21%. In all, 51% were found to originate from the right of the isthmus, 46% from the left and 2% from the midline. One patient had two pyramidal lobes. A significant number of patients having routine neck ultrasounds have an incidental finding of a pyramidal lobe. Ultrasound is an effective modality for the demonstration and classification of the pyramidal lobe, as well as identification of pathology. It is important for radiologists to be aware of this normal variation, as it may be the site of primary or recurrent thyroid pathology. Radiologists should report it where relevant to ensure adequate surgical treatment of pathological glands.

Ultrasonographic study of the incidence of pyramidal lobe and agenesis of the thyroid isthmus in Nnewi population

“…Our study showed that there was no incidence of agenesis of isthmus or the presence of pyramidal lobe in the study population. This is in contrast with an ultrasonic study on the incidence and morphological features of the pyramidal lobe of thyroid gland conducted by Mortensen et al (22) at Bristol, United Kingdom. They observed that out of the total number of subjects examined, a pyramidal lobe was found in 21% (90/416).…”

“…They attributed this high prevalence to a selection bias or the use of different diagnostic tools. Again, Mortensen et al , in their study on the incidence and morphological features of pyramidal lobe on thyroid ultrasound revealed the overall incidence of pyramidal lobe to be 21% among the study subjects (22) . A study on surgical anatomy of the pyramidal lobe and its significance in thyroid surgery reported that the pyramidal lobe was found in 61% of the cases (15) .…”

“…It is also important for radiologists to be aware of these normal variations (presence of pyramidal lobe and agenesis of the isthmus), as it may be the site of primary or recurrent thyroid pathology. Radiologists should report it where relevant to ensure adequate surgical treatment of pathological glands (22) . However, Deepa and Shrikrishna (2015) reported that developmental anomalies of the thyroid gland are quiet commonly seen.…”

“…Most of the variations are due to the partial persistence of the median or thyroglossal duct (28) . Pyramidal lobe and agenesis of the isthmus may be entirely an incidental finding, they can be affected by the same range of pathologies as the remainder of the thyroid, and hence it is important to identify this normal variant (22) . Therefore, knowledge of variations of the thyroid gland is substantial for surgeons dealing with head and neck surgery.…”

Anatomical Variations of Thyroid Glands in Northeastern-Thai Embalmed Cadavers

“…Thyroid gland abnormality was found in this research as a result of the emergence of pyramidal lobe (8.8 %). In the previous research conducted with different sample groups, with the diversities of the cadavers' nationalities and the places and the times of study, showed that the percentages of thyroid gland abnormality (18-66 %) were higher than the one found in this research (Braun et Begum et al;Joshi et al;Ozgur et al, 2011;Zivic et al, 2011;Park et al, 2012;Cengiz et al, 2013;Mortensen et al, 2014;Veerahanumaiah et al;Gurleyik et al, 2015;Rajkonwar & Kusre). In 2017, there was a reported case with pyramidal lobe emergence (Gurleyik et al) (Table III).…”