The pyramidal lobe: Clinical anatomy and its importance in thyroid surgery

Institute of Anatomy, Medical University Graz, Harrachgasse 21, Graz, 8010, Austria.
Surgical and Radiologic Anatomy (Impact Factor: 1.05). 03/2007; 29(1):21-7. DOI: 10.1007/s00276-006-0165-1
Source: PubMed


The pyramidal lobe could be a source of pitfalls in thyroidectomy, due to its frequency but unreliable preoperative diagnosis on scintigraphic images. Special attention has to be paid to the pyramidal lobe to avoid leavings of residual tissue when complete removal of the thyroid is indicated. Sixty cadaveric specimens were examined with special emphasis to the topographical anatomy and expansion of the pyramidal lobe. A pyramidal lobe was found to be present in 55% of the cadavers (32/58). It was found more frequently in men than in women. In men the median length was 14 mm and in women 29 mm. An accessory thyroid gland was present in one specimen, in four cases the isthmus was missing. The pyramidal lobe branched off more frequently from the left part of the isthmus (16) than from the right (7) or the midline (9). In two cases it originated from the left lobe. Additionally 23 scintigraphic images were analyzed to evaluate the visualization of a pyramidal lobe. Only three of them showed enlargements of the isthmus that could be taken as a pyramidal lobe. Due to its frequency the pyramidal lobe should be regarded as a normal component of the thyroid. It is not reliably diagnosed by scintigraphic imaging because scintigraphy can only give functional information but not morphological one. Therefore the anterior cervical region has to be investigated very carefully during operation in order not to leave residual thyroid tissue in total thyroidectomy.

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    • "Furthermore, the percentage of PL visualization by nuclear scan is approximately 15-20% [14-16]. These are the major drawbacks in thyroid surgery and can be a cause of incomplete resection of the gland; hence special attention has to be paid to PL [15, 16]. The anterior cervical region has to be investigated very carefully during thyroidectomies. "
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    ABSTRACT: Background Complete excision is important for proper surgical treatment of thyroid disorders. Functional thyroid tissue can be identified based on the level of serum thyroglobulin (Tg), which is produced only by the thyroid follicular cells, and nuclear scan. Methods Serum thyroid stimulating hormone (TSH), free thyroxin (FT4), basal (unstimulated) Tg and anti-Tg antibody (anti-Tg ab) were measured at the sixth postoperative month in 100 patients with benign thyroid disorders treated by total thyroidectomy. Thyroid nuclear scan was obtained to identify functional remnant of the thyroid gland. The sensitivity, specificity, accuracy, positive predictive value (PPV) and negative predictive value (NPV) of the Tg levels in assessing thyroid remnant were calculated. Results Positive scan showed thyroid remnant in 23 patients, among whom 16 were Tg positive (true positive) and seven were Tg negative (< 0.5 ng/mL) (false negative). In these patients, the nuclear scan revealed pyramidal lobe remnants. In 77 patients with negative scan, the Tg levels were also negative (true negative), and the PPV, NPV, sensitivity, specificity and accuracy of the Tg levels were 100%, 92%, 70%, 100% and 93%, respectively. Conclusions The positive basal Tg (> 0.5 ng/mL) level accurately indicated the functional thyroid remnant after total thyroidectomy. The negative Tg (< 0.5 ng/mL) level supported complete excision of the thyroid gland. The surgical completeness of total thyroidectomy was accurately evaluated based on the serum Tg levels. Therefore, serum Tg levels should be measured in postoperative follow-up to determine the completeness of total thyroidectomy.
    Journal of Clinical Medicine Research 10/2014; 6(5):369-73. DOI:10.14740/jocmr1873w
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    • "Detection of pyramidal lobe by radionuclide methods were reported at a rate ranging from 4.2 to 40% (3,4,5). It is lower compared to anatomic and surgical methods, and this is attributed to the fact that pyramidal lobe has quite a thin structure and it is not functionally active in patients who did not undergo thyroid operation (1,11). Esophageal activity may be confused with the pyramidal lobe on the scintigraphic images. "
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    ABSTRACT: Objective: The aim of this study is to investigate the presence of pyramidal lobe in thyroid scintigraphy and to compare the presence of pyramidal lobe in different thyroid pathologies between genders. Methods: Images of 866 patients (663 female, 203 male) with ages ranging from 8 to 85 were evaluated retrospectively. Presence of pyramidal lobe and its location were established in images. Patients were divided into groups in terms of gender, presence of nodular/diffuse goiter, thyroid function test results and rate of the presence of pyramidal lobe and whether a significant difference existed between the groups were calculated. Results: Of the 866 patients, 156 (18%) had pyramidal lobe observed in scintigraphy. Hundred and 26 (81%) of patients observed to have pyramidal lobe were female and 30 (19%) were male. Pyramidal lob stemmed from the left lobe in 76 (48%) patients, right lobe in 61 (40%) patients, and isthmus in 19 (12%) patients. Pyramidal lobe visualization rate was 18% for euthyroidism and hyperthyroidism, it was found as 15% for hypothyroidism. The rate of pyramidal lobe visualization was 13% in nodular goiter patients, 43% in diffuse goiter patients, and 20% in patients whose scintigraphy showed normal thyroid glands. In the statistical evaluation, rate of pyramidal lobe visualization in diffuse goiter patients was found to be significantly higher compared to other patients (p<0.001). Conclusion: Preoperative imaging of pyramidal lobe especially in patients requiring total thyroidectomy would decrease relapses that may occur later and thus facilitate the treatment and monitoring of patients. Conflict of interest:None declared.
    08/2013; 22(2):32-5. DOI:10.4274/Mirt.09719
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    • "In his report, Marshall noted that in 7% of the cases, one lobe was grossly larger than the other lobe and the isthmus was absent in 10% of the cases (Marshall, 1895). In another series of 58 cases, the isthmus was absent in 6.9% of the subjects (Braun et al., 2007). "
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    ABSTRACT: Historically, thyroid surgery has been fraught with complications. Injury to the recurrent laryngeal nerve, superior laryngeal nerve, or the parathyroid glands may result in profound life-long consequences for the patient. To minimize the morbidity of the operation, a surgeon must have an in-depth understanding of the anatomy of the thyroid and parathyroid glands and be able to apply this information to perform a safe and effective operation. This article will review the pertinent anatomy and embryology of the thyroid and parathyroid glands and the critical structures that lie in their proximity. This information should aid the surgeon in appropriate identification and preservation of the function of these structures and to avoid the pitfalls of the operation.
    Clinical Anatomy 01/2012; 25(1):19-31. DOI:10.1002/ca.21220 · 1.33 Impact Factor
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