Incidence of Pyramidal Lobe and Levator Glandulae Thyroideae of Thyroid Gland in Adult Cadavers: A Morphological Study With Its Surgical Perspective

Abstract

Background: Thyroid gland a brownish red, highly vascular endocrine gland consisting of two lateral lobes connected by an isthmus. It lies in front of the second, third and fourth tracheal rings. It is one of the commonest glands well known for its developmental anomalies, ranging from common to rare ones. The thyroid surgeon must have full knowledge of the anatomy of the thyroid gland, including all of its embryological, congenital, or acquired variations. Levator glandulae thyroideae (LGT), the persistent part of thyroglossal duct (fibromusculoglandular) stretches from the pyramidal lobe or upper border of isthmus of thyroid gland to the body of the hyoid bone, usually on the left side. Presence of the pyramidal lobe (thyroid tissue remnant of embryological origin located in the pretracheal region between the isthmus and the hyoid bone), may impact completeness of thyroidectomy. These variations will help the surgeons in planning thyroid surgeries in a better and safe way.Materials and Observations: Dissection was carried out routinely in 34 cadavers of both sexes in which 2 cadavers presented with LGT. In one cadaver LGT was extending from the left lobe of thyroid gland to hyoid bone. In the other cadaver in addition to the LGT, abnormal extent of the pyramidal lobe (PL). Thus accounting for an incidence of 5.80% variation, both the variations were noted in one male and one female cadavers. Conclusion:In the present study occurrence of thyroid anomalies (morphological variations) such as pyramidal lobes along with LGT is vital, while dealing with thyroid surgeries in the neck region to avoid iatrogenic injuries during complete removal of the gland tissue. Knowledge of embryology of thyroid gland is vital as complex underlying embryology produces substantial anatomic variations both in thyroid bed and elsewhere in the neck and mediastinum.