Metastatic papillary thyroid carcinoma with internal jugular vein tumor thrombus - A case report and review of the literature

Introduction

Papillary thyroid carcinoma (PTC)is common and accounts for approximately 80% of all thyroid malignancies (1). It is well known that some thyroid carcinoma may behave aggressively and tend to cause local invasion, recurrence, and distant metastasis (2). However, microscopic vascular invasion is common in all types of thyroid carcinoma (3). PTC rarely causes extension and growth that may involve the great veins, particularly the internal jugular vein, resulting in intraluminal tumor thrombus (4). In the current article, we present a rare case of metastatic PTC with intraluminal tumor thrombus in the internal jugular vein. We reviewed published data focusing mainly on vascular sites involved with tumor thrombus, diagnosis modalities, and the time of diagnosis preoperative vs. postoperative.

Case presentation

A 56-year-old male was referred to our outpatient endocrinology department in July 2023 with a three-month history of progressive enlargement of a right-sided anterior neck mass. His past medical and family history were unremarkable. Physical examination revealed a firm, non-tender 5 x 5 cm mass within an enlarged right thyroid lobe without palpable lymphadenopathy. Neck ultrasonography identified a 5.5 x 6.5 cm heterogeneous mass in the lateral aspect of the right thyroid lobe, along with a suspected thrombus in the internal jugular vein (IJV). Fine-needle aspiration (FNA) guided by ultrasonography confirmed a diagnosis of papillary thyroid carcinoma (PTC). Preoperative enhanced contrast computed tomography (CT) of the neck and chest demonstrated a heterogeneous 5.5 x 6.5 cm right thyroid mass with hypodense areas and poorly defined margins at the base of the right neck, showing lateral extension. The right internal jugular vein (RIJ) was enlarged and heterogeneous, with an extensive filling defect consistent with an intraluminal tumor thrombus. Additionally, an 8 mm lymph node in the right upper lobe of the lung was noted, raising suspicion for metastasis, though there was no evidence of pericardial or pleural effusion (Figure 1).

Figure 1. Contrast-enhanced computed tomography (CT) images of the neck and chest reveal a large nodule with areas of cystic degeneration within the right lobe of the thyroid gland. The yellow arrow indicates a tumor thrombus obstructing the right internal jugular vein (IJV).

After an extensive preoperative evaluation, including multidisciplinary consultation with a vascular surgeon team, in October 2023, the patient underwent a total thyroidectomy, right modified lymph node dissection, and resection of the internal jugular vein (IJV). Histopathological examination revealed a multifocal papillary thyroid carcinoma (PTC) measuring up to 7 cm, predominantly displaying a follicular growth pattern. There were cribriform and solid growth areas, with foci consistent with poorly differentiated carcinoma, constituting approximately 10-15% of the tumor volume. Evidence of vascular invasion was observed, including a large vein identified as the IJV containing a tumor thrombus. Invasion of the striated muscle was also noted. Metastatic carcinoma was detected in 3 of 26 lymph nodes, with the largest metastatic focus measuring 4 mm. The left thyroid lobe contained two foci of papillary thyroid microcarcinoma, each up to 5 mm, without extrathyroidal extension or vascular invasion. The IJV showed a tumor thrombus with fragments of PTC (Figure 2).

Figure 2. Histopathological examination revealed papillary thyroid carcinoma with a predominantly follicular growth pattern, along with areas consistent with poorly differentiated carcinoma. Vascular invasion was observed in a large vessel identified as the internal jugular vein, which contained a tumor thrombus (H&E staining; (A) ×10 magnification, (B) ×60 magnification).

In February 2024, the patient underwent radioiodine ablation therapy with a dose of 150 mCi and was prescribed levothyroxine at 200 mcg daily. Laboratory results showed suppressed thyroid-stimulating hormone (TSH) levels and undetectable thyroglobulin (Tg) levels with normal thyroglobulin antibodies (TgAbs).

At the one-year follow-up in July 2024, a neck ultrasound revealed a suspicious right lymph node measuring 11 x 6.5 x 5 mm at level 3. Positron emission tomography/computed tomography (PET/CT) demonstrated pathological FDG uptake in a 10 mm lymph node in the right mid-neck, along with pulmonary nodules suggestive of lung metastasis. Fine-needle aspiration (FNA) indicated the lymph node was suspicious for metastatic PTC. In August 2024, the patient underwent resection of the lymph node and a left modified neck dissection. The histological findings revealed a 1.3 cm lymph node at level 3 on the right side, which was almost totally replaced by papillary metastatic carcinoma of a poorly differentiated variant. Focally extranodal tumor extension less than 1 mm was also seen. Examination of the excised lymph node at level 3 on the left neck disclosed fragments of lymph node tissue and surrounding fibro-fatty tissues infiltrated by metastatic poorly differentiated thyroid carcinoma variant. The other 13 dissected lymph nodes at this level were free of tumor involvement. At level 2, nine lymph nodes were dissected and found to be free of tumor. At level 4, one lymph node measuring 3 mm out of eight lymph nodes revealed metastatic thyroid carcinoma. no extranodal extension was observed. Postoperatively, a detectable Tg of 9.4 mcg/L with normal TgAbs was observed. Therefore, the patient was referred to the oncology department for further evaluation, ongoing follow-up, and treatment.

Discussion

Tumour thrombosis of large vessels is commonly observed in angio-invasive malignancies, such as hepatocellular carcinoma and renal cell carcinoma, which frequently involve the portal vein, hepatic veins, renal veins, and the inferior vena cava (5, 6). In contrast, papillary thyroid carcinoma (PTC) typically spreads via the lymphatic system, with hematogenous dissemination leading to distant metastasis being rare (1). Microinvasion of cervical veins has been well documented in thyroid follicular and Hürthle cell carcinomas (2).

In this case report, we demonstrated the presence of an internal jugular vein (IJV) thrombus preoperatively. Reviewing the literature, we identified 50 cases of thyroid carcinoma associated with vascular tumor thrombus (Table 1). Among these patients, 34 were female, with a mean age of 56.8 years (range: 26–84 years). Most reports consist of case reports (34 cases) and case series (16 cases). Caudal extension of the thrombus was frequently observed, involving the brachiocephalic veins, superior vena cava, and, in some cases, propagation to the right atrium and tricuspid valve (7–44).

Table 1. Characteristics of patients with thyroid carcinoma and vascular tumor thrombus.

In contrast, proximal extension was rare, with only one case reporting involvement of the sigmoid sinus. Additionally, distant metastases to uncommon sites, including the vertebrae, pituitary gland, and skull bones, were reported (Table 1). Complications such as superior vena cava syndrome, pulmonary embolism, metastasis to different sites, and mortality were extensively reported in our manuscript.

Diagnosing vascular tumor thrombus can be clinically challenging and is highly dependent on the location and extent of the thrombus. However, dilated neck veins, upper limb edema, or extensive involvement of large vessels such as the jugular vein, subclavian vein, and superior vena cava should raise suspicion of tumor thrombus in this patient population. As highlighted in our case, preoperative imaging modalities, including Doppler ultrasonography (US) and contrast-enhanced computed tomography (CT), are essential for accurate diagnosis and surgical planning. Doppler US and contrast-enhanced CT were the most commonly used techniques to detect vascular tumor thrombus in the reviewed cases (Table 1). Contrast-enhanced CT is generally preferred due to its reliability, whereas the US is more operator-dependent, potentially limiting its accuracy.

Conclusions

Tumor thrombus is rare among patients with PTC. However, this entity should be considered, particularly in patients with signs of vascular involvement. Preoperative diagnosis using Doppler US and/or enhanced contrast CT is mandatory for a favorable outcome.

Author contributions

ZA: Conceptualization, Writing – original draft, Writing – review & editing. ES: Writing – original draft, Writing – review & editing. SK: Writing – original draft, Writing – review & editing.

Funding

The author(s) declare that no financial support was received for the research, authorship, and/or publication of this article.

Conflict of interest

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Generative AI statement

The author(s) declare that no Generative AI was used in the creation of this manuscript.

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