Morphological characteristics of developmental anomalies of the thyroid gland: a prospective single-center cohort study.

Background: Thyroid diverticulum originates between the first and second pharyngeal pouches, and descends via the thyroglossal duct to the level of CV to TI vertebra. By the 6th week of gestation the thyroglossal duct starts to obliterate. Failure in its obliteration causes differentiation of the distal part into the pyramidal lobe (PL), while the cranial portion may alter into a fibromuscular remnant - levator glandulae thyreoideae (LGT).

Materials And Methods: Morphological characteristics of PL and LGT were prospectively observed in 86 cadavers (66 male and 20 female).

Results: PL was observed in 59.3%, occurring more frequently in male cadavers (60.61%) compared to female cadavers (55%). PL was more frequent on the left side (50.98%) than on the right side (39.22%). Junctional PL was determined in 58.82%, isthmic PL in 27.45%, and lobar PL in 13.73%. The average height, width, and area of PL reached 23.81 mm, 13.13 mm, and 320.16 mm², respectively. The most frequent height-to-width ratio of PL was 1.3 : 1. LGT was observed in 47.67% of cadavers. LGT prevailed in male cadavers (48.48%) over female cadavers (45%). LGT occurred commonly on the left side (53.66%) than on the right side (31.71 %). Macroscopic evaluation demonstrated prevalence of fibrous LGTs (65.85%). Hyopyramidal type of LGT was observed in 70.73% of cadavers.

Conclusions: Knowledge gained from this study is applicable in the surgical field to reduce the risk of intraoperative and postoperative complications in thyroid surgery.