An unprecedented occurrence of incidental tonsillar ectopic primary Papillary Thyroid Carcinoma in an adult female: A case report

Introduction and Importance:

Any defect in the early phases of the normal complex embryogenic pathway might lead to anatomical anomalies that lead to the formation of ectopic thyroid gland tissue. Overall, ectopic thyroid tissue incidence is one in 300 000, and the rate of malignant transformation among those is merely 1%. However, documented cases of malignant transformation of ectopic thyroid tissue in the tonsils have not yet been – to the best of the knowledge – documented in published literature.

Case Presentation:

We illustrate the case of a 58-year-old female who was referred to the clinic after she underwent a tonsillectomy due to chronic discomfort and gradual difficulty in swallowing. Documentation of an ectopic primary Papillary Thyroid Carcinoma in one of the patient’s excised tonsils was achieved after thorough histopathological and immunohistochemical analyses took place. Radiological evaluation excluded any metastatic involvement and paved the path toward surgical intervention, which was comprised of a total thyroidectomy.

Clinical Discussion:

Surgical resection of the patient’s thyroid gland was achieved, and the subsequent histopathological analysis of the specimens revealed nodular hyperplasia with degenerative changes but without evidence of malignant transformation in her thyroid gland.

Conclusion:

Ectopic primary Papillary Thyroid Carcinoma is an immensely rare occurrence, regardless of population parameters. Its incidence could originate in various anatomical locations, but to the best of the knowledge, its incidence in the tonsils has not been previously documented in published literature. Adequate levels of clinical awareness in this situation could timely alleviate patient complaints and aid in performing optimal life-saving interventions.

Introduction

Highlights

• Ectopic thyroid tissue results from a developmental defect in the embryonic process.

• The occurrence of ectopic thyroid tissue is rare. The estimated incidence rate is merely 1 in 300 000 individuals.

• The rate of malignant transformation of ectopic thyroid gland tissue is ~1%.

• Several locations for ectopic primary Papillary Thyroid Carcinoma have been seen, but none were in the tonsils.

• Treatment for ectopic primary papillary thyroid carcinoma has yielded positive results, as the 10-year patient survival rate is above 90%.

Through embryogenesis, the thyroid gland passes through different stages of anatomical development and migrates along a preset path from the base of the pharynx toward its last settlement position anterior to the trachea. Any defect in this complex pathway, especially in the early phases, might lead to anatomical anomalies that lead to the rise of ectopic thyroid gland tissue in places it should not normally exist1,2. Patients symptoms could range from being completely asymptomatic to having hypersecreting tissue or even undergoing malignant transformation1,2. It is profoundly rare for an ectopic thyroid gland to occur. Therefore, the incidence rate is estimated to be 1 in 300 000 individuals3. As for incidence location, ectopic thyroid gland tissue is chiefly found at the thyroglossal, lingual, and laryngotracheal sites. There were also documented instances where it originated in sites next to the heart, pancreas, aorta, and esophagus. However, the estimated rate of malignant transformation of ectopic thyroid gland tissue is merely 1%4,5. Furthermore, numerous incidences are documented where innate malignancy of the thyroid gland itself is absent despite the presence of ectopic thyroid gland tissue malignant transformation. This was witnessed as a thyroglossal duct cyst6,7 and submandibular, unilateral, or bilateral cervical mass formations8–10, respectively. Moreover, it was also reported with a branchial cleft cyst11, and at different sites within the mediastinum12–14. To the best of our knowledge, there has been no previous documented case of an ectopic primary thyroid gland tissue carcinoma in the tonsils. This makes our case the first documented case of its kind. The work has been reported in line with the SCARE criteria and the revised 2020 SCARE guidelines15.

Presentation of case

Patient information

We present the case of a 58-year-old female with a known history of hypertension for 4 years prior to admission. She sought our surgical clinic as a referral for the purpose of consultation after her newly diagnosed and treated tonsillar ectopic primary Papillary Thyroid Carcinoma (PTC). The patient’s history began 2 years prior to admission as sudden but gradual progressive dysphagia and neck discomfort not associated with the ingestion of solids or liquids. The symptoms were felt on the left side in the submandibular region. No odynophagia was felt; no hoarseness of voice was reported, and no precipitating or relieving factors were reported. Symptoms of hypothyroidism/hyperthyroidism were denied. Furthermore, no fever, night sweats, unintentional weight changes, or general fatigue were experienced. At first, she visited an external outpatient clinic and received conservative therapy. However, the symptoms did not completely subside, but rather were spontaneously aggravated 3 months prior to admission. Therefore, her otolaryngologist performed a tonsillectomy to relieve the patient of her symptoms after seeing her markedly hypertrophied left tonsil. The patient’s symptoms were completely relieved after the operation. The results of the subsequent postoperative histopathological analysis of the excised specimens revealed a left tonsillar ectopic primary PTC (Fig. 1A–E). Furthermore, immunohistochemical staining was performed. Results included positive staining for Cytokeratin 7, whereas it stained negatively for Thyroid Transcription Factor-1, Epithelial Membrane Antigen, and Estrogen Receptor. The right tonsil was free of any neoplastic involvement. Afterward, she was referred to our specialized General Surgery Clinic for follow-up and appropriate management of her thyroid gland. Her surgical history only involved a diagnostic cardiac catheterization 4 years prior. Her drug history only included an oral antihypertensive medication. She has negative allergic, psychosocial, and family histories. She denied being exposed to any arsenic, chemotherapeutic/radiotherapeutic agents, or a similar previous incidence in the past. Her BMI was 29 kg/m².

Figure 1.

(A) Histopathological analysis via H&E staining revealing the ectopic primary Papillary Thyroid Carcinoma. (B) Histopathological analysis via H&E staining revealing the microscopic features of the Papillary Thyroid Carcinoma, such as ground glass appearance and intranuclear grooves. (C) Histopathological analysis via H&E staining revealing both kinds of histological components (Upper half includes the normal tonsillar tissue, whereas the lower half includes the ectopic primary Papillary Thyroid Carcinoma). (D–E) Histopathological analysis via H&E staining revealing tonsil tissue that is composed of normal squamous nonkeratinized stratified epithelium. The submucosa reveals multiple variable sized hyperplastic lymphatic follicles with germinal centers, with marked infiltration by tumor composed of complex, randomly oriented papillae with fibrovascular cores. Said papillae are lined by cuboidal cells, while the nuclei are overlapping with clear chromatin and nuclear grooves.

Clinical findings

Physical examination was normal, as no notable anomalies were detected through inspection, palpation, or auscultation of the involved neck region. Preoperative laboratory investigations results were within normal ranges, especially her thyroid gland’s hormonal panel.

Diagnostic assessment

To begin our preoperative radiological assessment, a thyroid gland ultrasonographic scan was performed. The thyroid gland appeared normal in size. However, multiple small nodules were visualized in both lobes of the gland. Some of them appeared hyperechoic and included calcifications, whereas others appeared hypoechoic with well-demarcated borders. The largest of which had diameters of 6 and 7 mm in the right and left lobes, respectively. Vascularization appeared within normal limits. No lymphadenopathy was seen on either side of the neck. To procure an enhanced insight into the situation and to exclude any possible metastasis, a multi-slice Computed Tomography (CT) scan was performed. It conformed with the findings of the previously done ultrasound and further demonstrated thyroid gland heterogeneity without a frank mass formation (Fig. 2). The pan-CT’s remaining findings in the chest, abdomen, and pelvis revealed no tumor involvement. Furthermore, a Pertechnetate Thyroid Scintigraphy via Technetium-99m (Tc-99m) was performed. It was concluded that the thyroid gland was in normal position and morphology, except for a mild increase in size. The radioactive uptake by the thyroid tissue was mildly but consistently increased. Said uptake reached (4.7%). No frank thyroid nodules were visualized, and no abnormal radioactive material uptake by the thyroid gland tissue was demonstrated (Fig. 3). To conclude our preoperative radiological assessment, an Iodine 123 whole body scan was performed. Results reported no abnormal uptake of radioactive iodine in the anterior neck region, the chest, or any other body part (Fig. 4). Classical steps taken to prepare the patient for surgery included setting up an intravenous line, providing preoperative prophylactic antibiotics, and taking blood samples for crossmatching. Fortunately, we were not confronted with any obstacles.

Figure 2.

Preoperative multi-slice computed tomography image with contrast in cross-sectional view further demonstrating thyroid gland heterogeneity without a frank mass formation (blue arrow). The trachea is displayed via the orange arrow.

Figure 3.

Tc-99m scan was performed. It concluded that the thyroid gland was of normal position and morphology, except for a mild increase in size. Radioactive uptake by the thyroid tissue was homogenously mildly increased. Said uptake reached 4.7%. No frank thyroid nodules were visualized, and no abnormal radioactive material uptake by the thyroid gland tissue was demonstrated.

Figure 4.

Iodine 123 whole body scan was performed. Results reported that no abnormal uptake of radioactive iodine in the anterior neck region, the chest, or any other body part.

Therapeutic intervention

A total thyroidectomy was successfully accomplished at our tertiary university hospital. It was performed by a professor of General Surgery and a first assistant in general surgery with 38 and 5 years of experience, respectively. The therapeutic surgical treatment was carried out under general anesthesia without any notable perioperative complications. Intraoperatively, the thyroid gland was carefully isolated and resected while sparing the parathyroid glands. No vivid mass formation was noticed. We directly sent the excised thyroid tissue to a specialized histopathology laboratory for meticulous analysis. Postsurgical histopathological analysis of said specimens was done via Hematoxylin and Eosin (H&E) staining. It revealed a normal-sized thyroid gland with an intact capsule. The left lobe included colloid tissue with colloid nodules, the largest of which measured (0.7 cm). The right lobe included multiple colloid nodules, the largest of which also measured (0.7 cm). The results conform to nodular hyperplasia with degenerative changes (Fig. 5A–E). The patient went through an uneventful postoperative recovery and was discharged to the outpatient setting within 3 days of the operation. Sterile applied wound dressings by healthcare providers were done in a regular frequency, and prophylactic postoperative intravenous antibiotics were administered. She was then referred to a specialized oncology clinic to undergo the necessary follow-up and treatment. Lastly, she has been medically surveilled for 11 months thus far. Regular clinical visitations at our specialized clinic took place to ensure her successful recovery. Clinical evaluations through physical examination and ultrasonography were done and yielded satisfactory results.

Figure 5.

(A–E) Histopathological analysis via hematoxylin and eosin staining of the excised thyroid tissue. It revealed a normal-sized thyroid gland with an intact capsule. The left lobe included colloid tissue with colloid nodules, the largest of which measured (0.7 cm). The right lobe included multiple colloid nodules, the largest of which also measured (0.7 cm). The results conform with nodular hyperplasia with degenerative changes.

Discussion

Originating from the endodermal cell layer of the foregut, the thyroid diverticulum arises and later migrates down into the neck region while keeping a patent link to the tongue via the thyroglossal duct16. Numerous embryological anomalies could take place during the sensitive phase of passing through toward the last pretracheal placement. These anomalies could result in the formation of ectopic thyroid gland tissue1. Carcinoma of the thyroid gland is considered a rare entity that mainly affects the pediatric population. In turn, it makes up almost 3% of all pediatric and adolescent population group neoplasia17. Furthermore, PTC belongs to a class of differentiated thyroid tumors, and it is considered the most prevalent type of thyroid gland malignancy, where it forms almost 80% of this gland’s neoplastic subtypes18. Regarding ectopic thyroid gland carcinoma, it has been documented in sites like the mediastinum9, lingua19, and the thyroglossal duct20. Moreover, the most prevalent occurrence sites for ectopic thyroid gland tissue are the laryngotracheal, lingual, and thyroglossal ducts. Several other distinct sites have been witnessed, such as the aorta, esophagus, heart, and duodenum9. The documented incidence rate of ectopic thyroid gland tissue is estimated to be 1 in 300 000 individuals, where it favors occurrence in females rather than males with a gender-specific ratio of 4 : 121. On the one hand, physicians ought to suspect the presence of ectopic thyroid gland tissue when presented with a patient suffering from a neck mass formation above the level of the thyroid gland. However, the percentage of any malignant transformation of said mass is estimated to be less than 1%22. Radiological diagnostic modalities utilized to detect ectopic thyroid gland tissue consist of ultrasound, scintigraphy, CT, or MRI. Nonetheless, there is still a chance of false-positive radiological results1. Patient treatment for PTC has yielded positive results, as the prognosis is good with a 10-year patient survival rate rising above 90%23,24. Treatment modalities vary. We have surgical intervention, radioactive iodine, chemotherapy, and radiotherapy. This has been proposed according to the contemporary management guidelines for individuals with thyroid gland cancer developed by the American Thyroid Association25. Lastly, when it comes to instances of an ectopic primary thyroid gland tissue carcinoma, there is a scarcity of available published data on the subject. Moreover, no current evidence-based regulations have been set to guide physicians toward the ideal treatment option(s)26. Thyroidectomy accompanied by neck dissection of the ipsilateral side and followed by adjuvant radioactive iodine therapy has been proposed by Simion et al.27.

Conclusion

Ectopic primary PTC is an immensely rare occurrence, regardless of population age, ethnicity, or gender group. Its incidence could happen in various anatomical locations, but to the best of our knowledge, its incidence in the tonsils has not been previously documented in the published literature. Upholding adequate levels of clinical awareness of this clinical situation could timely alleviate patient complaints and aid in performing optimal life-saving interventions. Physicians should be extremely motivated to document these instances to facilitate the conveyance of research studies that help define vital epidemiological parameters. This expands physicians’ aptitudes to aptly diagnose and treat such a malignancy.

Ethics approval

N/A.

Consent of patient

Written informed consent was obtained from the patient for the publication of this case report and accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal on request.

Sources of funding

None.

Author contributions

O.A.: Conceptualization, resources, who wrote, original drafted, edited, visualized, validated, literature reviewed the manuscript, and the corresponding author who submitted the paper for publication.

G.A., E.A.: Supervision, visualization, validation, resources, literature review, and review of the manuscript.

W.A.: Histopathologist and cytologist who aided in histopathological analysis of the microscopic specimens, in addition to validation and review of the manuscript.

M.M.: 1st surgical assistant in the operation, supervision, project administration, validation, resources, and review of the manuscript.

M.A.: General Surgery professor who performed and supervised the operation, in addition to supervision, project administration, and review of the manuscript.

Conflicts of interest disclosure

None.

Research registration unique identifying number (UIN)

N/A.

Guarantor

Omar Al Laham.

Availability of data and materials

The datasets generated during and/or analyzed during the current study are not publicly available because the Data were obtained from the hospital computer-based in-house system. Data are available from the corresponding author upon reasonable request.

Provenance and peer review

Not commissioned, externally peer-reviewed.

Acknowledgments

Department of Pathology, Al Assad University Hospital, Damascus University, Damascus, (The) Syrian Arab Republic. Department of Radiology, Al Assad University Hospital, Damascus University, Damascus, (The) Syrian Arab Republic.