Rapidly Expanding Neck Mass

Case Presentation

A 66-year-old man was referred to endocrinology after his primary care provider noted a soft, mildly enlarged thyroid during examination, with thyroid ultrasound showing the right lobe measuring 5.6 cm × 3.0 cm × 5.5 cm and the left lobe measuring 6.2 cm × 2.2 cm × 3.4 cm, with numerous nodules measuring up to 2.4 cm and 2.2 cm in the right and left lobes, respectively. Fine needle aspiration (FNAs) of 2 moderately suspicious (thyroid imaging reporting & data system [TI-RADS 4]) nodules was performed, one resulted with atypia of undetermined significance and the other with benign-appearing follicular cells. FNA was repeated for the lesion with atypia 5 months later, which demonstrated the same result. The specimen was sent for thyroid-specific molecular testing, including BRAF, RET, and RAS mutations, which was pending when the patient presented to the emergency department with hoarseness and difficulty swallowing; on examination, a 4-cm firm and smooth swelling was noted on the right side of the neck. A magnetic resonance image of the neck showed a diffusely enlarged thyroid gland with heterogeneous coarse attenuation and few nodules in the right lobe (Fig. 1) and a lobulated soft tissue mass in the right level II abutting the right common carotid artery (Fig. 2). An otorhinolaryngologist was immediately consulted, and a core needle biopsy was performed that day. Given the rapid growth of the mass, the patient was subsequently admitted, and he underwent tracheostomy for a compromised airway. The core biopsy specimen of the nodule showed pleomorphic spindled cells with scattered large/giant cells with cherry-red macronucleoli, numerous mitotic figures, and necrotic areas (Fig. 3).

Fig. 1.

Fig. 2.

Fig. 3.

What is the diagnosis?

Answer

Metastatic anaplastic thyroid cancer. Anaplastic thyroid cancer is a type of undifferentiated thyroid follicular epithelial tumor that is highly aggressive and has poor treatment outcomes, with a median survival rate of <6 months.¹ Making a diagnosis using FNA in a patient with a history of multinodular goiter is not uncommon. Regional metastases involving the skin, muscles, and great vessels of the neck and mediastinum are common at the time of initial diagnosis; however, distant metastases can also be found in up to 50 percent of patients, the most common site being the lungs, followed by the brain.² As seen in Fig. 1, Fig. 2 (magnetic resonance imaging of the neck), a rapidly enlarging neck mass can cause neck pain, tenderness, hoarseness, dyspnea, dysphagia, and cough. Although FNA cytology can yield a diagnosis, a core biopsy may be necessary to obtain adequate material for molecular testing and immunostaining to establish the final diagnosis. His original molecular testing result was positive for NRAS mutation, and next-generation sequencing with PD-L1 immunohistochemistry (22C3) on the core needle biopsy showed this in addition to a tumor proportion score of 60%. He received cytotoxic therapy immediately after diagnosis but was transferred to a specialty center and is currently being treated with a tyrosine kinase inhibitor and PD-L1 inhibitor.

Disclosure

The authors have no multiplicity of interest to disclose. The views expressed in this article are those of the authors and do not reflect the official policy or position of the Department of the Army, Department of the Navy, Department of Defense, or the U.S. Government.