Neck schwannoma diagnosed by core needle biopsy: a case report

Abstract

Here we present a case of a 58 year old man referred to our hospital to undergo neck and thyroid ultrasonography (US) following palpable neck mass. US revealed a solid hypoechoic nodule in right thyroid lobe, and a solid lesion on the right laterocervical neck region with ultrasound suspicious features of neoplastic lymph node. In order to achieve a diagnosis of the neck mass and to get a proper evaluation of the thyroid nodule, we decided to perform a fine-needle aspiration (FNA) of both lesions. At cytopathologic examination the thyroid nodule appeared as benign, while cytologic sampling of the neck lesion was inadequate for a proper evaluation. Thus, we performed core needle biopsy (CNB) of the neck lesion like recently proposed for thyroid lesions; also, to definitively exclude malignancy of thyroid nodule, this also underwent CNB. Histologic report of CNB confirmed benign thyroid nodule, while the neck lesion revealed a proliferation of neuronal type consistent with schwannoma. The patient has been addressed to clinical and ultrasonographic follow-up. CNB appears as a safe and minimally-invasive approach to diagnose indeterminate neck masses and avoid unnecessary diagnostic surgery.

Case report

A 58 year old man was referred to our hospital to undergo neck and thyroid ultrasound examination (US) due to a recently discovered palpable neck mass. The patient was in good general health, and no relevant anamnestic details were recorded. A blood sampling for thyrotropin, free-T4, calcitonin and anti-thyroid antibodies showed values within the reference ranges. US revealed a solid hypoechoic thyroid nodules in the right lobe, appearing with peripheral flow at Color Doppler signal. Concomitant US of the neck identified a lesion on the right middle laterocervical region. It appeared as a 2-cm round hypoechoic lesion, homogeneous in its aspect, with regular margins and with no increased signal at Color and Power Doppler evaluation. In particular, no hylar vascularity consistent with reactive lymph node [1] was detected (Fig. 1a).

Fig. 1.

Ultrasound presentation of the neck mass

In order to achieve a diagnosis of the neck lesion and to get a proper evaluation of the thyroid nodule, we decided to perform a fine-needle aspiration (FNA) of the pericentimetric lesion of the right thyroid lobe. Also, to exclude a metastatic lymph node from occult thyroid cancer, FNA was performed on the neck lesion with cytologic examination and thyroglobulin and calcitonin measurement in washout fluids of the needle after aspiration [2–4] using 23-gauge needles in ultrasound-guided freehand technique. At cytopathologic examination the thyroid nodule appeared as benign (Thy 2). Cytologic specimens of the neck lesion had inadequate report, while thyroglobulin and calcitonin in washout fluids were undetectable and excluded metastasis from thyroid [2, 3]. Thus, we decided to perform a core needle biopsy (CNB) of the neck mass. After administration of local anesthesia by mepivacain 1 % mL, a 21-gauge modified Menghini cutting needle (Biomol^®, Hospital Service, Rome, Italy) was percutaneously introduced under ultrasound guide in freehand fashion, as recently described for thyroid lesions [5] (Fig. 1b). CNB was also performed in thyroid nodule to avoid the possibility of false negative results at FNA [6]. All core samples were formalin-fixed. No complications occurred and the patient was discharged three hours later. Histopathologic results of the thyroid nodule fitted with cytopathologic findings, confirming benignancy. The histologic examination of the neck lesion revealed a mesenchymal proliferation of neuronal type, without cellular atypia nor mitotic activity. The immunohistochemical panel was negative for Galectin-3, HBME-1, Cytokeratin-19, and positive for S100 protein, consistent with schwannoma (Fig. 2). These findings allowed to avoid diagnostic surgery and patient has been addressed to clinical and ultrasonographic follow-up.

Fig. 2.

Histology of the schwannoma of the lateral neck

Discussion

Thyroid carcinoma, especially the papillary type, most often metastasizes to cervical lymph nodes [3] and it is not uncommon to find thyroid cancer metastatic neck lesions at the time of disease presentation even when the primary tumor is small and intrathyroidal. Such metastatic neck lesions are up to 20–50 % in thyroid papillary carcinoma [7]. Over the last decades, FNA for cytopathological evaluation of thyroid lesions proved to be a reliable tool, recommended by current guidelines [7]. Besides, cervical lymph nodes are also related to non-head and neck metastatic cancer or even to tuberculous lymphadenitis or other benign lymphadenitis, such as Kikuchi’s disease, Kimura’s disease, and Rosai–Dorfman disease [1, 3, 8].

Several US aspects have been described as useful features in differentiating between benign and malignant neck lymphadenopathy [9] and US coupled with FNA has been described as ideal first approach investigation in distinguishing between lymphomatous and metastatic neck lymph nodes from thyroid cancer. On the other hand, peripheral nerve sheath tumors are common neoplasms but they can be diagnostically challenging on occasions, and controversies about their classification and grading still persist, along with the primary debate about benignancy versus malignancy [10]. Nevertheless, the role of FNA in soft tissue tumors and tumor-like lesions remains controversial [11] with a non-negligible rate of unsatisfactory samples [12].

CNB performed by 14-gauge tru-cut trocar has been proposed and some retrospective studies compared its role to FNA [12] with the conclusion that CNB appeared to be useful in case of non-diagnosing samplings. More recently, a paper by Kasraejan et al. [13] showed the results of a prospective study focused on extremity soft tissue tumors, summarizing that CNB had a bigger sensitivity, specificity, predictive value and accuracy than FNA in determining malignancy, but still appearing inferior to open surgical biopsy, which in the paper has been considered worthwhile whenever possible. The major limit of CNB in neck mass resides in heterogeneity of mesenchymal tumors, so large lesions may result not adequately sampled by thin core needle. On the other hand CNB is informative in a great number of cases and it was recommended as diagnostic strategy for neck masses in international guidelines [14]. With relation to the case report we are presenting, some aspects can be of interest concerning the role of CNB. Firstly, it helped us to rule out a possible metastatic thyroid disease which would have driven to completely different diagnostic and therapeutic choices, with no preliminary open surgical biopsy of the lymph node needed, provided it had been adequately evaluated by CNB. Besides, CNB of the neck lesion was performed by a 21-gauge needle, which in other papers concerning thyroid biopsy proved to have a good tolerability by patients [15], with low complication rates [5]. Focusing on soft tissue tumors, in our opinion more studies would be necessary in order to establish the proper role of CNB within the diagnostic work-up [16]. For example, CNB could be of value in patients with unsatisfactory FNA not eligible to radical surgery, in order to get the most accurate minimally-invasive histological and immunoistochemical characterization to address the therapy. Nevertheless, in the case we are presenting, CNB acted as a minimally-invasive, safe, not expensive procedure able to prove benignancy of the neck lesion, thus allowing for a follow-up programme.

Conclusions

The role of CNB in soft tissue tumors has not been completely defined yet. In our opinion, the use of a 21-gauge needle for CNB procedures can have a role in reducing morbidity. Based on the herein case report, CNB looks a safe and minimally-invasive approach to indeterminate or suspicious neck mass, and allows to avoid diagnostic surgery of benign lesions.