Thyroid nodules, pseudonodules and large segments: from empirics to reality

I read with interest the article by Kok et al. “Thyroid nodules that disappear—a case report on pseudonodules in thyroiditis” (1). The authors presented a case of unilateral subacute thyroiditis (ST) localized in a large segment of the gland lobe. I note that both signs (one-sidedness and changes in a large segment of the lobe) became the strength of this publication, since they indicate a key feature of the pathogenesis of ST. However, these signs went unnoticed by the authors, who focused on other phenomena.

Unfortunately, the unscientific term “pseudonodule” has become entrenched in ultrasound thyroidology. This concept includes all local non-nodal changes in the parenchyma of the gland. Specialists try to designate them with numbers and use such empirical designations as “giraffe”, “Swiss cheese” and others (2,3). All these variants of pseudonodules have a different morpho-functional basis and look different on ultrasound. As you can see, the meaning of the term “pseudonodule” is associated with opposition, instead of using words that explain the main feature of the local pathological process. This ambiguity with the term “pseudonodule” contributes to errors in clinical practice. Among other things, this situation led the authors of the article to a distorted perception of reality.

In the article, ultrasound images of Fig. 1 show a large segment (1), consisting of medium-sized segments (surrounded by hypoechoic contours), in which some lobules (small segments) have signs of destruction and lymphocytic infiltration (significantly hypoechoic). The large segment was not completely measured in length (the authors measured only parts of this segment).

These segments were already present before the disease, since the parenchyma of a healthy thyroid consists of such segments of different levels (4). Each thyroid segment is controlled by neurocytes of the autonomic nervous system (4). Usually large and meddle-sized segments are not visible in a healthy thyroid. But under the influence of excessive nerve stimuli, the tissue of a particular segment can become overstrained and change (4). Reducing excess neural stimulation and subsequent normalization of neural regulation can lead to restoration of segment tissue.

This neural principle of the pathogenesis of ST is indicated by the data in the presented case. Infectious and genetic hypotheses of the pathogenesis of ST cannot explain the unilateral change in the gland. Moreover, the defeat of one large segment. It is impossible to imagine conditions in which viruses and bacteria affect only one lobe or its segment. There are other features that cause some experts to doubt the infectious basis of the pathogenesis of ST (5). In addition, the unilateral variant of ST occurs in almost 40% of patients (6).

In their article, the authors correctly draw attention to the indication for needle biopsy (1). As can be seen, the authors did not know about the segmental structure of the thyroid gland and initially mistook a large segment for a real nodule [this feature is indicated by the authors’ text and the American College of Radiologist Thyroid Imaging Reporting and Data System (ACR-TIRADS) level, used only for nodules]. Of course, the authors doubted it. Therefore, differential diagnosis was used. Unfortunately, almost all specialists do not know about the segmental structure and activity of the thyroid gland and often perform puncture of large segments, mistaking them for nodules.

Due to the unknown about the segmental structure of the thyroid, the authors misunderstood the processes in the gland. In their opinion, the large pseudonodule (25 mm) turned into a small one (5 mm). In reality, there was a normal recovery for most of the large segment. Most of the tissue in this segment has recovered in the same way as usually occurs in ST. But one of several meddle-sized segments remained changed. In addition, the lack of information on the volume of the thyroid lobes before and after treatment reduces the value of the article on the disappearance of a large nodule. Control ultrasound images (after treatment; Fig. 3) taken in a different plane (1) also limit the understanding of the treatment result.

The authors used the bright expression “Thyroid nodules that disappear” in the title of the article and thereby identified the key idea of the article. Such an expression presupposes at least a hypothetical disclosure of the basis of natural magic. In particular, the authors designated the recovery process as “spontaneous resolution of thyroid nodules”, but also did not explain its morpho-functional basis. Why “spontaneous”? How did “resolution” happen? Where did the stromal swelling, lymphocytes and elements of tissue destruction disappear from the large segment? To help the authors, I can offer a simple solution: the immune system (lymphocytes) utilizes destroyed tissue elements and promotes regeneration (7).

Despite my clarifications, the article has great scientific potential. Features of the course of the disease in the patient reveal the basis of the pathogenesis of ST and show the features of morphofunctional processes in the thyroid. The merit of the authors is that they noticed an unusual manifestation of the disease (subacute inflammation in a large segment of the gland), excluded the indication for a puncture biopsy and wrote an article. After all, such cases of damage to individual large segments in Hashimoto’s thyroiditis lead to significant errors. The absence of signs of ST and the unknown segmental structure of the thyroid do not allow us to make the same differential diagnosis as the authors of the article. As a result, such patients are unreasonably performed with a puncture biopsy and even have the gland removed.

Acknowledgments

The author would like to thank the authors of the article and the Editor of the journal for the opportunity to read interesting publications.

Funding: None.

Footnote

Provenance and Peer Review: This article was a standard submission to the journal. The article did not undergo external peer review.

Conflicts of Interest: The author has completed the ICMJE uniform disclosure form (available at https://aot.amegroups.com/article/view/10.21037/aot-24-23/coif). The author has no conflicts of interest to declare.

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References

1. Kok CYZ, Liew H, Khoo HW, et al. Thyroid nodules that disappear — a case report on pseudonodules in thyroiditis. Ann Thyroid 2024;9:3. [Crossref]
2. Duick DS, Lupo MA, Levine RA. editors. Thyroid and Parathyroid Ultrasound and Ultrasound-Guided FNA. Cham: Springer International Publishing; 2018:546.
3. Eldeiry LS, Laver NMV, Randolph GW, et al. Handbook of Thyroid and Neck Ultrasonography. An Illustrated Case Compendium with Clinical and Pathologic Correlation. Cham: Springer Cham; 2023:241.
4. Ushakov AV. Principles and features of ultrasound hypoechogenicity in diffuse thyroid pathology. Quant Imaging Med Surg 2024;14:2655-70. [Crossref] [PubMed]
5. Desailloud R, Hober D. Viruses and thyroiditis: an update. Virol J 2009;6:5. [Crossref] [PubMed]
6. Sencar ME, Calapkulu M, Sakiz D, et al. The contribution of ultrasonographic findings to the prognosis of subacute thyroiditis. Arch Endocrinol Metab 2020;64:306-11. [Crossref] [PubMed]
7. Tishevskaya NV, Babaeva AG, Gevorkyan NM. The role of lymphocytic RNA in the intercellular information exchange and in the regulation of regenerative processes. Ross Fiziol Zh Im I M Sechenova 2016;102:1280-301. [PubMed]