Schwannoma of the neck simulating a thyroid nodule

Primary schwannoma of the thyroid gland: analysis of case characteristics and review of the literature

BACKGROUND

To improve the characteristics of primary thyroid schwannomas (PTS) and to provide reference basis for clinical diagnosis and treatment.

METHODS

PubMed was searched for case reports of PTS up to December 2022 using the search terms "Thyroid nerve sheath tumor" or "Thyroid schwannoma" or "Thyroid Neurilemmoma", respectively. 34 cases were screened.

RESULTS

PTS can occur at any age, nodules averaged 3.9 cm. The most common symptoms were voice change and dysphagia. Fine needle aspiration cytology showing spindle-shaped cells should be considered for schwannoma. Most cases underwent thyroid lobectomy or nodule removal with a good prognosis. Tissue types with both Antoni A and Antoni B features are common. Positive immunohistochemical staining for S-100 protein, CD34 and waveform proteins helped confirm the diagnosis.

CONCLUSIONS

Positive immunohistochemistry for S-100 and wave proteins helps confirm the diagnosis. Preoperative diagnosis is challenging, but pathology and immunohistochemical staining are the gold standard for diagnosis. The first choice of treatment is surgical resection of the nodules, the prognosis is good.

Thyroid-Bed Schwannoma Mimicking a Thyroid Neoplasm: A Challenging Diagnosis: Report of a Case and Literature Review

Background: Schwannomas, also called neurinomas, are rare benign tumors of the neural cells that can develop from the sheaths of nervous structures of several districts, although the most frequent sites are the cranial nerves (25%–45%). Rarely, cases show neck schwannomas in the thyroid parenchyma, while the cases of thyroid-bed schwannomas mimicking a thyroid-gland lesions are anecdotal. Methods: We report the case of a 70-year-old man with a preoperative-imaging diagnosis of a thyroid neoplasm, confirmed as Thyr 4 by fine-needle cytology. Results: During surgery, an extra-thyroidal lesion was discovered, determined to be a neck schwannoma through definitive pathology. A literature review of cases of thyroid-bed-lesion schwannomas misinterpreted as thyroid neoplasms was carried out. Conclusions: In the case of suspicious extra-thyroidal lesions, we advocate for a close routine cooperation between the cytologist, the radiologist, and the surgeon in the attempt to reach an accurate preoperative diagnosis.

Schwannoma of the thyroid bed: A case report and review of the literature

RATIONALE

Schwannomas involving the thyroid gland are very rare and only a few cases have been reported in the literature. However, previous reports did not distinguish between thyroid bed schwannomas and intrathyroidal schwannomas. Here, we report a thyroid bed schwannoma mimicking a malignant thyroid nodule and review the literature on thyroid bed schwannomas.

PATIENT CONCERNS

A 33-year-old woman presented at our hospital with mild neck swelling.

DIAGNOSIS

Thyroid ultrasound revealed a well-defined, oval-shaped, markedly hypoechoic solid nodule with echogenic foci suggesting macro- and microcalcifications in the left thyroid gland. The lesion was considered a "highly suspicious" intrathyroidal nodule, based on the guidelines for the assessment of thyroid nodules. Fine needle aspiration was performed twice, but the cytological results were nondiagnostic.

INTERVENTIONS

Left thyroidectomy was performed, and schwannoma of the thyroid bed was confirmed on histopathologic analysis.

OUTCOMES

The patient was in a stable condition after surgery, and the thyroid function test results were within the normal range.

LESSONS

Diagnosis of a schwannoma of the thyroid bed is challenging because its incidence is extremely low, and it is often misdiagnosed as an intrathyroidal nodule on ultrasonography. Therefore, it is advisable to adopt a diagnostic strategy to perform additional core needle biopsy in cases of thyroid nodules with nondiagnostic fine needle aspiration results and to consider the location of the lesion more carefully to determine the suitable therapy.

Primary thyroid schwannoma masquerading as a thyroid nodule

The thyroid gland is a very rare site for head and neck schwannomas. Till date there have been only 19 reported cases in English literature. Only 25% of schwannomas occur in the head and neck region, most of them arising in relation to the peripheral nerves and cervical sympathetic chain. We report a similar case, with clinical and sonological features of a benign thyroid nodule. The diagnosis of schwannoma was established on the final histopathology report and a review of the slides and the imaging was done to confirm the site of origin. A thorough review of earlier reported cases was done. We summarize the existing knowledge on this entity, emphasizing the challenge of diagnosing it pre-operatively.

Ancient schwannoma mimicking a thyroid mass with retrosternal extension

We report the case of a middle-aged hypothyroid woman presenting with a neck swelling, voice change and breathing difficulty. On evaluation, she was diagnosed to have goitre with retrosternal extension. The mass was surgically excised and a histopathological report of ancient schwannoma was obtained. A review of literature on schwannomas of the head and neck was carried out. An ancient schwannoma should be considered as one of the differential diagnosis of a cervical mass, even though the clinical presentation point towards a thyroid swelling. At 6 months follow-up, the patient was found to be asymptomatic except for a hoarse voice.

Primary peripheral nerve sheath tumors of the thyroid gland

BACKGROUND

Primary peripheral nerve sheath tumors (PNSTs) of the thyroid gland are exceptionally rare tumors that usually present as asymptomatic neck nodules in adults. This article presents a literature review of these tumors.

SUMMARY

PNSTs of the thyroid can be classified into benign and malignant. Only three cases of malignant PNSTs have been reported. Benign PNSTs of the thyroid include neurofibromas and schwannomas. Only two cases of isolated neurofibroma of the thyroid have been reported. Schwannomas are typically benign, slow-growing tumors that originate from neuronal schwann cells, with a clinical picture depending on the anatomic size and site. Pathologically, schwannomas are classified into Antoni A and Antoni B. Only 17 cases of schwannomas of the thyroid exist in literature to date.

CONCLUSIONS

Schwannomas of the thyroid gland are extremely rare and usually asymptomatic. Complete surgical resection is mandatory for care.

Neck lesions mimicking thyroid pathology

INTRODUCTION

Nodular lesions within the neck may origin from several structures. A misdiagnosed origin may expose the surgeon to inappropriate procedures. These lesions are paradoxically frequent in high specialised centre for endocrine surgery.

PATIENTS AND METHODS

In the year 2006, three patients were first admitted to our department with a diagnosis of thyroid nodule (1) or lymphatic metastases of thyroid carcinoma (2). The first patient had ultrasound (US) and Tc-99-m scan orienting for thyroid nodule. The two other patients, presented with lateral neck lesion in ipsilateral sincronous and previous diagnosis of papillary thyroid carcinoma, respectively, with US and computed tomography scan confirmed lesion but with a FNA cytology negative for tumoural cells.

RESULTS

All three patients underwent surgical exploration. In the first two cases, a whitish tender nodule (4 and 4.5cm), cleavable from surrounding structures, was removed with final histology of Schwannoma and Paraganglioma, respectively. Both patients experienced Bernard Horner Syndrome. In the last patients, a firm grey nodule of 5cm strictly adherent to muscular planes was removed with diagnosis of Castleman's Disease.

CONCLUSIONS

Nodular neck lesions mimicking a thyroid pathology (thyroid nodules or metastatic lymph nodes) are rare but can represent a tough challenge for surgeons who might fall into incorrect surgical approaches, resulting in high morbidity. Pre-operative work-up would help the surgeon to obtain the correct diagnosis, thus, to follow the better surgical approach. Nevertheless, a careful approach would be used for that neurogenic tumour amenable of resection without jeopardising nervous structures.

Neural tumours of the neck presenting as thyroid nodules: a report of three cases

OBJECTIVES

Neural tumours of the neck may at times secondarily involve the thyroid and manifest clinically as thyroid nodules. On cytological evaluation these nodules may be confused with other spindle lesions of the thyroid. We report two cases of schwannoma and one case of a malignant peripheral nerve sheath tumour (MPNST) of the neck, which presented as thyroid nodules and evaluate the role of cytology in identifying these tumours.

METHODS

The thyroid nodules in all the three cases were sampled by the non-aspiration technique using a 23-gauge needle. Both alcohol-fixed and air-dried smears were prepared and stained by the Papanicolaou and May-Grünwald-Giemsa stains. Cytology smears and histology sections from the resected specimens were reviewed, and the findings noted.

RESULTS

Both the cases of schwannoma were correctly identified on cytology while the case of MPNST could only be typed as a spindle cell tumour. However, on cytology it was not possible to state whether the tumours were thyroidal or extrathyroidal in origin.

CONCLUSIONS

Schwannomas of the neck are easily identifiable on cytology compared with MPNST. However, cytology alone is not helpful in identifying the origin of these tumours. As primary neural tumours of the thyroid are rare, the possibility of a soft tissue neural tumour extending into the thyroid should always be ruled out while evaluating these cases.