Comparison of the Incidence of Postoperative Hypothyroidism in Patients Undergoing Conventional Thyroid Lobectomy and Pyramid- and Isthmus-Preserving Lobectomy

Hypothyroidism is a recognized sequela of conventional thyroid lobectomy. However, there have been no studies on the incidence of hypothyroidism following the preservation of the isthmus and pyramid during lobectomy. Therefore, in the present study, we compared the incidence of hypothyroidism following conventional lobectomy and lobectomy during which the isthmus and pyramidal lobe were preserved. Data for a total of 65 patients collected between September 2018 and April 2019 were reviewed retrospectively. Circulating thyroid-stimulating hormone (TSH) concentration was measured before and after surgery in a group who underwent conventional thyroid lobectomy (n = 29) and in a group in which the isthmus and pyramid were preserved (n = 36). We found no significant difference in TSH concentration between the two groups before surgery, or 3 months or 1 year after surgery. Thus, there might be no difference in the incidence of postoperative hypothyroidism between patients who undergo conventional thyroid lobectomy and those in which the isthmus and pyramid are preserved.

Ultrasonographic Evaluation of the Pyramidal Lobe of the Thyroid Gland in Infants and Children in Western Turkey Between 2018 and 2020

Background: The pyramidal lobe (PL) is a common anatomic variation of the thyroid gland with a reported prevalence of over 50% in adult series, but to the best of our knowledge, there are no data in the literature regarding its characteristics in the pediatric population. Objectives: The aim of this study was to evaluate the prevalence, anatomic, and morphological features of the PL in pediatric participants on thyroid ultrasonography (US). Methods: The descriptive cross-sectional study design was used. Between November 2018 and January 2020, the US images obtained from 325 participants with normal thyroid glands were retrospectively evaluated. The presence, location, size, volume, the morphology of the base, and continuity or separation from the thyroid gland were noted for each PL. Results: The PL was present in 34.1% (110/325) of the pediatric participants. It was more frequent in girls than in boys. In all, 56.4% were found to originate from the left of the midline of the isthmus. One patient had double PL. The mean anteroposterior, transverse, and longitudinal diameters were 2.5 ± 1.4, 2.7 ± 1.3, and 5.6 ± 2.5 mm, respectively. The median volume of the PL was 15.11 mm3. PL was longer in girls compared to boys; however, these changes were not significant (5.8 vs. 5.1, P = 0.406, respectively). A total of 63.6% of the PLs were with a wide base and narrow apex, and 36.4% were with a thin base size the same as the apex size. A separation of the PL from the thyroid was not observed. Conclusion: The present study showed, for the first time, that the age of the children is positively correlated with the size and volume of the PL. The prevalence and location of the PL were consistent with those reported in the adult population.

Thyroid fibrous band and levator glandulae thyroideae muscle: Two different structures associated with the pyramidal lobe of the thyroid gland

We investigated two structures that are in close association with the pyramidal lobe of the thyroid gland. Our investigation was performed using microdissection and histological examination in 106 human postmortem specimens. The first investigated structure was identified as the thyroid fibrous band that was present in 28.3% of cases. This band was always associated with the pyramidal lobe (which was significantly longer and thicker when associated with this band) and it had a constant hyo-pyramidal extension; it was located close to the midsagittal plane and predominantly composed of dense irregular connective tissue. The second investigated structure was the levator glandulae thyroideae muscle, which was associated with the pyramidal lobe in only 13.6% of cases. This muscle had a double extension, hyo-pyramidal and laryngo-pyramidal, located farther from the midsagittal plane, it was longer and thinner than the thyroid fibrous band and predominantly composed of striated muscle fibers. We confirmed our hypothesis that the thyroid fibrous band, which may be considered as the partial fibrous remnant of the thyroglossal duct and levator glandulae thyroideae, and which may be considered as infrahyoid or laryngeal muscle, are two different structures of the thyroid gland.

Persistent hyperthyroidism in a patient after total thyroidectomy: the thyroid anatomy has implications for treatment

Introduction. Grave’s disease (GD) can be treated using three modalities: anti-thyroid medications, radioactive iodine therapy (RAI), or surgery. If surgery is selected, total thyroidectomy is the procedure of choice. Patients with hyperthyroidism frequently have an enlarged thyroid gland, occasionally with a pyramidal lobe. Aim. We point the usefulness of thyroid scintigraphy, which provides valuable information regarding the thyroid anatomy. Description of the case. The manuscript presents a case report of 43-year-old woman with unstable Grave’s disease, who underwent thyroidectomy and developed persistent hyperthyroidism postoperatively. She was referred by an endocrinologist to a nuclear medicine outpatient clinic for RAI therapy. I-iodide scintigraphy revealed two foci with excessive tracer accumulation. One of the foci in the middle of the neck corresponded to the pyramidal lobe. Conclusion. The thyroid anatomy anomalies can lead to unnecessary implications for treatment. Identifying the pyramidal lobe preoperatively and removing it from patients requiring total thyroidectomy may decrease the recurrence rate of hyperthyroidism. Thyroid scintigraphy is a useful diagnostic tool to visualize the pyramidal lobe.

Pathology

Grossly, thyroid enlargement in Hashimoto's thyroiditis (HT) is generally symmetrical, often with a characteristic conspicuous pyramidal lobe. The tissue involved by HT is pinkish-tan to frankly yellowish in color and tends to have a rubbery firmness. There is no necrosis or calcification. The capsule is intact and non-adherent to peri-thyroid structures. Microscopically, there is a diffuse process consisting of a combination of epithelial cell destruction, lymphoid cellular infiltration, and fibrosis. Lymphocytes are predominantly T-cells and plasma cells. Most infiltrating T-cells have α/β T-cell receptors. Gamma/delta T-cells are rare. Hashimoto's thyroiditis has been graded based on lymphocytic infiltration seen on cytology, into Grades 0-III, where Grade 0 means no lymphoid cells and Grade III severe lymphoid cell infiltration. Deposits of dense material representing IgG are found along the basement membrane on electron microscopy. This chapter explores the pathology of Hashimoto's disease.