CASE REPORT |
https://doi.org/10.5005/jp-journals-10002-1449 |
Unexpected Diagnosis for a Common Lesion: Schwannoma of Thyroid Gland - A Case Report
1,2Department of General Surgery, Madurai Medical College, Chennai, Tamil Nadu, India
Corresponding Author: Rasik Fareed, Department of General Surgery, Madurai Medical College, Chennai, Tamil Nadu, India, Phone: +91 9884128913, e-mail: rasikinmmc@gmail.com
Received on: 20 April 2023; Accepted on: 20 July 2023; Published on: 31 August 2023
ABSTRACT
The thyroid gland is one of the uncommon locations for a head and neck schwannoma with an incidence of 25%, head and neck schwannomas arise from the cervical sympathetic chain, and peripheral nerves. They usually mimic a benign thyroid lesion or sometimes malignancy. This is a report of a suspicious thyroid nodule which turned out to be a schwannoma. We summarize previously reported cases with an emphasis on establishing preoperative diagnosis.
How to cite this article: Fareed R, Ramachandran J. Unexpected Diagnosis for a Common Lesion: Schwannoma of Thyroid Gland - A Case Report. World J Endoc Surg 2023;15(1):23–26.
Source of support: Nil
Conflict of interest: None
Patient consent statement: The author(s) have obtained written informed consent from the patient’s parents/legal guardians for publication of the case report details and related images.
Keywords: Case report, Fine needle aspiration, Schwannoma, Thyroid nodule
INTRODUCTION
The thyroid gland is an uncommon location for head and neck schwannoma and was first reported by Verocay in 1908.1 These lesions often mimic a benign nodule of the thyroid and similar imaging along with a paucity of cells on FNAC makes preoperative diagnosis very challenging. We have reported a case of such a masquerading lesion and also a review of ten previously reported cases.
CASE DESCRIPTION
A 16-year-old female presented with swelling in front of her neck for 6 months with no compressive symptoms. On examination, a firm single nodule of size 4 × 3 cm nodule was palpable in the left lobe of the thyroid (Fig. 1). Ultrasound (USG) of the neck revealed a 4.3 × 3.2 × 2.1 cm nodule in the left lobe of the thyroid with altered echoes and microcalcification. FNAC of the lesion showed thyroid follicular epithelial cells which are arranged in a monolayer sheet, clusters, and scattered in blood mixed colloid background. In view of suspected malignancy, the patient was planned for total thyroidectomy and intraoperatively, a firm enlarged left lobe with cystic lesions and multiple nodules in the right lobe was noted.
Fig. 1: Clinical picture
Gross appearance showed a 4 × 2.5 × 2 cm nodular left thyroid swelling with a cut surface showing grey white nodule measuring 2 cm in diameter (Fig. 2). Histology shows thyroid parenchyma and a well-circumscribed nodule of spindle-shaped cells arranged in sheets with intervening vascular spaces with areas of palisading nucleus (Figs 3 and 4). IHC with S100 was strongly positive and was diagnosed as a schwannoma of the thyroid gland with degenerative changes.
Fig. 2: Gross specimen
Fig. 3: Microscopic section of spindle cells in sheets (Antoni A)
Fig. 4: Microscopic section showing well-encapsulated spindle cell lesion with surrounding colloid
DISCUSSION
Neural tumors of the thyroid may be benign or malignant with benign tumors being schwannomas and neurofibromas. Although schwannomas of the head and neck region are relatively common, schwannomas involving the thyroid gland are quite rare with reports of intrathyroidal schwannomas in the literature (Table 1). Primary thyroid schwannomas originate from the intrathyroid sensory nerves or from autonomic innervation to the thyroid.3 Due to the rarity of this lesion, a review of the FNAC slides showed spindle cells intervening with thyroid colloid which was earlier thought to be fibroblasts. The USG images showed microcalcification which was suggestive of malignancy, but, in fact, was due to cystic degeneration of the schwannoma. Calcification in a schwannoma is highly uncommon, which can make it difficult to establish a differential diagnosis. Even though calcification is a normal finding indicating degenerative changes, only a few reported cases have described calcification in schwannoma.4,6 Though the FNAC turned out to be benign, the imaging findings of hypoechogenicity and microcalcifications mimicked malignancy, and hence a total thyroidectomy proceeded.
Presentation | USG | FNAC | CT scan | Surgery done | IHC | Review of FNAC slides | |
---|---|---|---|---|---|---|---|
Delaney and Fry et al.2 | Asymptomatic neck swelling | – | – | – | Hemithyroidectomy | – | – |
De Paoli et al.1 | Enlarging neck mass with foreign body sensation in the throat | Hypoechoic nodule with rich vascularity | USG-guided aspirate—inconclusive | – | Total thyroidectomy done in view of suspected malignancy | S 100 +ve | Aggregate of spindle cells seen on previous slides |
Subramaniam et al.9 | Asymptomatic neck swelling | Thyroid nodule with large cystic degeneration | Colloid goiter | – | Hemithyroidectomy | – | – |
An et al.10 | Asymptomatic neck swelling | Hypoechoic nodule with cystic changes | Paucicellular aspirate with few round cells and spindle cells | Well-enhancing homogeneous mass | Hemithyroidectomy | S 100 +ve | – |
Kandil et al.14 | Neck swelling with hoarseness and dysphagia | – | Inconclusive | Enhancing thyroid mass compressing the esophagus | Hemi- thyroidectomy | S 100 +ve vimentin +ve | – |
Sugita et al.11 | Asymptomatic neck swelling | Well-defined solid thyroid lesion | Inflammatory cells seen inconclusive | Low-density mass on plain CT and moderately enhancing on contrast | Hemithyroidectomy | – | – |
Jayaram4 | Asymptomatic neck swelling | Hypoechoic nodule | USG-guided aspirate—palisading pattern of spindle cells s/o schwannoma | – | Hemithyroidectomy | S 100 +ve | Both final histology and FNAC slides were indicative of schwannoma |
Aron et al.12 | Asymptomatic neck swelling | Hypoechoic nodule with cystic spaces | USG-guided aspirates s/o schwannoma | – | Hemithyroidectomy | – | Both final histology and FNAC slides were indicative of schwannoma |
Mikosch et al.13 | Asymptomatic neck swelling | Hypoechoic thyroid nodule | USG-guided FNAC—suspicious of neural tumor | – | Hemithyroidectomy | – | – |
Dhar et al.15 | Progressive neck swelling | Hypoechoic solid lesion adjacent to right lobe | Benign lesion | Heterogeneously enhancing lesion with multiple cystic spaces | Hemi- thyroidectomy | – | Antoni A and B with Verocay bodies |
Delaney and Fry et al.2 | Asymptomatic neck swelling | – | – | – | Hemithyroidectomy | – | – |
De Paoli et al.1 | Enlarging neck mass with foreign body sensation in the throat | Hypoechoic nodule with rich vascularity | USG-guided aspirate—inconclusive | – | Total thyroidectomy done i/v/o suspected malignancy | S 100 +ve | Aggregate of spindle cells seen on previous slides |
Subramaniam et al.9 | Asymptomatic neck swelling | Thyroid nodule with large cystic degeneration | Colloid goiter | – | Hemithyroidectomy | – | – |
An et al.10 | Asymptomatic neck swelling | Hypoechoic nodule with cystic changes | Paucicellular aspirate with few round cells and spindle cells | Well-enhancing homogeneous mass | Hemithyroidectomy | S 100 +ve | – |
Kandil et al.14 | Neck swelling with hoarseness and dysphagia | – | Inconclusive | Enhancing thyroid mass compressing the esophagus | Hemithyroidectomy | S 100+ve vimentin +ve | – |
Sugita et al.11 | Asymptomatic neck swelling | Well-defined solid thyroid lesion | Inflammatory cells seen inconclusive | Low-density mass on plain CT and moderately enhancing on contrast | Hemithyroidectomy | – | – |
Jayaram4 | Asymptomatic neck swelling | Hypoechoic nodule | USG-guided aspirate—palisading pattern of spindle cells s/o schwannoma | – | Hemithyroidectomy | S 100 +ve | Both final histology and FNAC slides were indicative of schwannoma |
Aron et al.12 | Asymptomatic neck swelling | Hypoechoic nodule with cystic spaces | USG-guided aspirates s/o schwannoma | – | Hemithyroidectomy | – | Both final histology and FNAC slides were indicative of schwannoma |
Mikosch et al.13 | Asymptomatic neck swelling | Hypoechoic thyroid nodule | USG-guided FNAC—suspicious of neural tumor | – | Hemithyroidectomy | – | – |
Dhar et al.15 | Progressive neck swelling | Hypoechoic solid lesion adjacent to the right lobe | Benign lesion | Heterogeneously enhancing lesions with multiple cystic spaces | Hemithyroidectomy | – | Antoni A and B with Verocay bodies |
The FNAC is universally available for investigation and sensitive for most of the head and neck masses. However, for the diagnosis of schwannoma, the sensitivity of FNAC is quite low, at 0–40% with IHC being the ideal investigation in such cases.7,8
Schwannoma of the thyroid gland is a rare entity. It resembles a benign nodule in presentation and imaging. Prompt suspicion and use of image-guided FNAC, IHC, and intraoperative frozen section can improve preprocedure diagnosis.
ORCID
Rasik Fareed https://orcid.org/0000-0002-0484-7140
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