A Cervical Schwannoma Masquerading as a Thyroid Nodule

Abstract

Background: We present a case of a cervical schwannoma, likely originating from the pharyngeal plexus of the vagal nerve. The lesion masqueraded as a thyroid nodule and magnetic resonance imaging (MRI) assisted in preoperative diagnosis. We review the radiographic characteristics of nerve sheath tumors on MRI as well as the diagnostic cytologic stains which can enhance the possibility of a correct preoperative diagnosis. Case: We describe a 60-year-old female with dysphagia and a neck mass consistent with a nodular goiter. The patient's history, diagnostic images, cytology, pathology, and surgical management are presented and analyzed. The preoperative diagnosis of a cervical schwannoma was suspected by the use of MRI which led to additional specialized cytologic stains. Conclusion: Pharyngeal wall schwannomas are important to consider in the differential diagnosis of thyroid nodules when fine needle aspiration cytology indicates cells of neural origin. Imaging by MRI can assist in identifying lesions of neural origin masquerading as thyroid nodules.

Cytologic and histological features of rare nonepithelial and nonlymphoid tumors of the thyroid

“…A nerve sheath tumor is determined to be primary by the fact that the tumor arises within thyroid parenchyma 20‐24 . Peripheral nerve sheath tumors (PNSTs) of the thyroid account for <0.02% of all thyroid tumors.…”

“…They usually present as a gradually enlarging mass without specific symptoms and signs. While 25% to 45% of schwannomas occur in the head and neck region, they are extremely rare in the thyroid 1,2,20‐25 . Isolated neurofibromas of the thyroid are also extremely rare 23,24 .…”

“…MPNSTs are exceptionally rare in children and most often affect older adults 1,2,18,21,22 . Malignant transformation of a PNST in the thyroid has been documented, but this is extremely rare 1,2,20 .…”

“…A nerve sheath tumor is determined to be primary by the fact that the tumor arises within thyroid parenchyma. [20][21][22][23][24] Peripheral nerve sheath tumors (PNSTs) of the thyroid account for <0.02% of all thyroid tumors. The morphological criteria used to diagnose a PNST of the thyroid gland are identical to those used for benign (schwannoma, neurofibroma) and malignant peripheral nerve sheath tumors (MPNSTs) in other body sites.…”

“…The morphological criteria used to diagnose a PNST of the thyroid gland are identical to those used for benign (schwannoma, neurofibroma) and malignant peripheral nerve sheath tumors (MPNSTs) in other body sites. 1,2,[20][21][22][23][24][25][26][27][28][29][30][31][32] PNSTs are difficult to diagnose based on clinical findings and sonographic features alone because they are similar to those of other thyroid entities.…”