Pyramidal lobe of thyroid

Last revised by Yuranga Weerakkody on 30 Jan 2021

The pyramidal lobe of thyroid (also known as Lalouette pyramid 5) is a normal anatomic variant representing a superior sliver of thyroid tissue arising from the thyroid isthmus. It is seen as a third thyroid lobe and is present in 10-30% of the population.

It represents a persistent remnant of the thyroglossal duct. It usually arises from the right or left side of the isthmus extending in a cranial direction; pyramidal lobes arising directly from the midline of the isthmus were rare in a large ultrasound study, accounting for only 2% of the cases 3

It is not uncommon to see it on routine thyroid ultrasound, a study of 416 patients in 2014 found it in 21% 3.

All the pathologies that may be seen in the normal thyroid are also seen in the pyramidal lobe.

A band of fibrous tissue may be present extending superiorly from the pyramidal lobe to the hyoid bone, sometimes with a skeletal muscle component, termed the levator glandulae thyroideae muscle 4.

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