Parapharyngeal metastasis from papillary thyroid carcinoma: a case diagnosed by thyroglobulin measurement in peroral fine-needle aspiration of a cystic metastatic lymph node

Parapharyngeal Lymph Node Metastasis From Papillary Thyroid Carcinoma

Metastatic parapharyngeal lymph nodes (LNs) from papillary thyroid carcinomas (PTC) are uncommon and can easily remain undetected. We describe a case that involves a 62-year-old woman treated for a PTC, who presented a rise in serum thyroglobulin (TG) levels. A computed tomography scan was performed, and revealed metastatic nodes in the left parapharyngeal space (PPS). A surgical resection of the nodes was performed with external cervical approach. A histological exam confirmed the diagnosis of a metastatic LN of a PTC. The aim of this report is to emphasize on the possibility of parapharyngeal metastatic nodes in PTC and to describe the diagnosis methods, treatment options, and impact on the prognosis.

Cystic lymph node metastasis of papillary thyroid cancer. Clinical facts

BACKGROUND

The therapy planning for cystic cervical lesions is dizzying. Although it is mostly a benign disease, it can also be a cystic lymph node metastasis with the origin of papillary thyroid cancer (PTC).

METHODS

Included were all patients with histological confirmed PTC, who underwent a thyroid resection from January 2012 to December 2017 (n=680). Analyzed were demographic data including family history and radiation exposure, preoperative workup including thyroid ultrasound and laboratory test of the TSH value complimented by fine-needle aspiration in case of suspected malignancy, and clinicopathologic features. This study aimed to specify preoperative findings and patients´ clinical presentation with cystic lymph node metastasis of PTC.

RESULTS

In 0.7% (5/680) of all patients with PTC a cystic cervical lesion was histologically confirmed as cystic lymph node metastasis. Preoperatively, only two of these patients were suspected of lymph node metastasis with unknown origin. In three patients, the resected cystic lymph node metastases were the only lymphatic metastasis. Interestingly 80% (4/5) of the patients suffered from papillary microcarcinoma (MPTC).

CONCLUSIONS

Cervical cystic lesions may be challenging in diagnostics and therapy. Although the recommended thyroid ultrasound may detect no pathological findings, a papillary microcarcinoma can be the primary tumor.

Occult papillary thyroid cancer presenting as cystic metastasis of the lateral neck: A case report

RATIONALE

Papillary thyroid cancer accounts for up to 85% of all cases of thyroid carcinoma. This disease entity is notorious for metastatic invasion of adjacent lymph nodes, including the cervical lymph nodes, potentially presenting as a growing lateral neck mass. However, these lesions tend to be recognized and diagnosed soon due to the palpable mass.

PATIENT CONCERNS

This report describes a very rare case of a huge slow-growing neck metastasis based on a 6 mm papillary thyroid microcarcinoma. This patient presented with a painless, but continuously growing right lateral neck mass. Aside from that, no specific complaints were mentioned.

DIAGNOSIS

The underlying cause of this patient's neck mass turned out to be an occult papillary thyroid microcarcinoma (Ø 6 mm) with metastatic invasion and subsequent cystic degeneration of cervical lymph nodes. Accurate diagnosis was made after surgical intervention through histopathological analysis.

INTERVENTIONS

The patient underwent complete resection of the cervical mass in conjunction with total thyroidectomy and right cervical neck dissection, followed by adjuvant iodine- and chemotherapy.

OUTCOME

Margin free surgical resection without any postoperative complications could be achieved. The patient received iodine supplementation and remained free of recurrence during regular clinical follow-ups for 2 years. The therapy was curative.

LESSONS

This case report emphasizes the importance of a thorough diagnostic work-up including preoperative tissue sampling of any cervical neck mass, since a benign appearance on imaging does not exclude a malignant process.

The first report of bilateral retropharyngeal lymph node metastasis from papillary thyroid carcinoma and review of the literature

The sites of lymph node metastasis of papillary thyroid carcinomas are typically the paratracheal and jugular lymph nodes. On the other hand, metastasis to the retropharyngeal or parapharyngeal nodes from papillary thyroid carcinomas is very rare. During the last two decades, limited to cases with a histologically definite diagnosis by surgery, only 39 cases have been reported. All reported cases were unilateral retropharyngeal or parapharyngeal node metastasis except one metachronous bilateral case, and there were no reports of simultaneous bilateral cases within our literature review. We report three cases of retropharyngeal node metastasis from thyroid papillary carcinoma, including a case of bilateral nodal metastasis. Retropharyngeal node metastasis was successfully resected in all three patients by the transcervical approach. As pointed out in past reports, this report also suggests that prior neck dissection and/or metastasis to cervical lymph nodes might alter the direction of lymphatic drainage to the retrograde fashion, resulting in the unusual metastasis to the retropharyngeal lymph nodes, and there is a possibility of a bilateral pattern. Also, it is necessary to consider the possibility of metastasis from a papillary thyroid carcinoma in the differential diagnosis of lymph node swelling in the parapharyngeal space.

Rare metastases of differentiated thyroid carcinoma: pictorial review

Differentiated thyroid cancer (DTC) is usually indolent with good prognosis and long-term survival. However, DTC distant metastasis is often a grave event and accounts for most of its disease-specific mortality. The major sites of distant metastases are the lung and bone. Metastases to the brain, breast, liver, kidney, muscle, and skin are rare or relatively rare. Nevertheless, recognizing rare metastases from DTC has a significant impact on the clinical decision making and prognosis of patients. (131)I single photon emission computed tomography/computed tomography ((131)I-SPECT/CT) can provide both metabolic and anatomic information about a lesion; therefore, it can better localize and define the (131)I-WBS findings in DTC patients. In this pictorial review, the imaging features of a range of rare metastases from DTC are demonstrated, with a particular emphasis on the (131)I-SPECT/CT diagnostic aspect.

Localization and identification of parapharyngeal metastases from differentiated thyroid carcinoma by 131I-SPECT/CT

BACKGROUND

Parapharyngeal metastasis is a rare event in differentiated thyroid carcinoma (DTC). The (131) I-single photon emission CT (SPECT)/CT allows better localization and definition for metastases in DTC. The aim of this study was to assess the value of (131) I-SPECT/CT for the diagnosis of parapharyngeal metastasis in patients with DTC.

METHODS

Consecutive patients with DTC (n = 561) treated with (131) I for the ablation of remnant or treatment of metastases were enrolled. A (131) I-SPECT/CT was performed when there were abnormal findings indicative of parapharyngeal metastasis on (131) I-whole-body scan (WBS).

RESULTS

A total of 15 lesions were found to be parapharyngeal metastasis in 14 of 561 patients with DTC after the use of (131) I-SPECT/CT. The incidence rate of parapharyngeal metastasis was about 2.5% in DTC. Of the 15 lesions, only 5 lesions were CT-positive. The remaining 10 lesions were either ignored or indeterminate by the CT alone.

CONCLUSION

The (131) I-SPECT/CT can identify parapharyngeal metastasis at an early stage. Parapharyngeal metastasis in DTC is relatively frequent after the use of (131) I-SPECT/CT.

The role of MR imaging in detecting nodal disease in thyroidectomy patients with rising thyroglobulin levels

BACKGROUND AND PURPOSE

One of the dilemmas facing clinicians treating patients with thyroid cancer is the evaluation of postthyroidectomy patients with rising serum thyroglobulin levels and indeterminate or normal findings on neck sonography. In this study, we examine the role of MR imaging in this subgroup of patients.

MATERIALS AND METHODS

We retrospectively reviewed MR images of patients with thyroid cancer with abnormal lymph nodes in the retropharyngeal and parapharyngeal spaces and determined the size and signal-intensity characteristics of these nodes. We reviewed patient charts for the following history: 1) thyroidectomy, 2) rising thyroglobulin levels, 3) iodine-131 radiation therapy, 4) neck dissection, and 5) pathology on neck sonography and chest CT. We reviewed pathology findings to determine if thyroid cancer metastases were present in these lymph nodes.

RESULTS

Eight patients had abnormal retropharyngeal space nodes, and 1 patient had a parapharyngeal space mass. Lymph nodes ranged from 7 to 25 mm. On MR imaging, 1 patient had a cystic node, 2 had complex nodes, and 6 had solid nodes. Eight patients had rising serum thyroglobulin levels and a history of thyroidectomy, radioiodine therapy, and neck dissection. Two of these patients had no pathologic nodes on sonography and normal findings on chest CT. Six patients had tissue sampling of their skull base node, and metastatic thyroid cancer was present in 5.

CONCLUSIONS

MR imaging of the neck should be considered in thyroidectomy patients with rising serum thyroglobulin levels and a history of radioiodine therapy and neck dissection. Radiologists should carefully examine the retropharyngeal and parapharyngeal spaces in these patients because nodal metastases may occur there more commonly than realized.

Utility of Thyroglobulin measurement in fine-needle aspiration biopsy specimens of lymph nodes in the diagnosis of recurrent thyroid carcinoma

Introduction

The most common site for the metastasis of papillary carcinoma of the thyroid (PTC) is regional lymph nodes. Ultrasound (US) imaging may identify abnormal appearing lymph nodes, suspicious for PTC recurrence. Although fine needle aspiration biopsy (FNAB) of abnormal lymph nodes is often diagnostic of recurrence, small or cystic lymph nodes may be non-diagnostic due to lack of tumor cells. The measurement of thyroglobulin (TG) levels in FNAB specimens from lymph nodes suspicious for recurrent PTC can serve as an adjunct to the cytologic diagnosis.

Materials and methods

115 abnormal appearing lymph nodes were aspirated under ultrasound guidance in 89 patients with history of thyroid carcinoma. In addition to obtaining material for cytologic interpretation, an additional aspirate was obtained by FNAB and rinsed in 1 ml of normal saline for TG level measurements.

Results

The cytologic diagnoses included: 35 (30%) reactive lymph node, no tumor seen (NTS), 39 (34%) PTC, 23 (20%) inadequate for evaluation due to lack of lymphoid or epithelial cells (NDX) 15 (13%) atypical/suspicious for PTC, and 3 (3%) other (e.g. paraganglioma, poorly differentiated carcinoma and carcinoma not otherwise specified). TG levels were markedly elevated (median 312 ng/ml; normal < 10 ng/ml) in 28 (72%) cases of PTC lymph node recurrence identified on cytology. TG measurements were also elevated in 5 lymph nodes classified as NTS and 4 NDX on cytology which resulted in 5 and 3 carcinoma diagnoses respectively on histological follow-up. Of the 9 atypical/suspicious cases with elevated TG levels all resulted in carcinoma diagnoses on follow-up.

Conclusion

The measurement of TG in FNAB specimens from lymph node in patients with history of PTC is useful in detecting recurrent disease, especially in cases when the specimen is known to be or likely to be inadequate for cytologic evaluation.