PMC

(A) Photograph of the patient's right neck demonstrating subdermal recurrences that occurred post surgery and chemoradiation, while on single-agent pembrolizumab. (B and C) Axial CT image at the level of the larynx demonstrates postoperative changes. Heterogeneously enhancing dermal and subdermal lesions in the right neck (white arrows) are hypermetabolic on the concurrent FDG-PET/CT (black arrows) and compatible with recurrent tumor. (D and E) The patient resumed the triple combination therapy (dabrafenib, trametinib, pembrolizumab) and achieved a complete resolution of metastatic lesions on exam and FDG-PET with excellent quality of life.

(A) FDG-PET/CT after treatment with dabrafenib, trametinib, and pembrolizumab demonstrates dramatic improvement in the neck disease, with residual foci of hypermetabolism in the left neck and superior mediastinum. (B) Posttreatment axial CT image now demonstrates a fat plane between the left thyroid lobe and the prevertebral soft tissues and the esophagus (small white arrow). Mass effect and tracheal deviation has resolved. Posteriorly, the left vertebral artery is no longer encased (black arrow), and anteriorly there is now a fat plane with the sternocleidomastoid (large white arrow). (C) Axial CT image at the level of the oropharynx shows that the left carotid artery is no longer encased (white arrow), and tumor involvement at the left pharyngeal wall and at the strap muscle has resolved. The patient underwent total thyroidectomy with en bloc resection of esophageal muscularis, bilateral central compartment dissection, bilateral level II–Vb neck dissection, preserving the bilateral recurrent laryngeal nerves and two parathyroid glands shortly after achieving a partial response to therapy. He then received radiation to the neck with radiosensitizing chemotherapy plus pembrolizumab. (D) A coronal view of the postoperative radiation planning CT scan. The red and blue lines represent the 60 Gy and 57 Gy isodose lines, respectively, while the color-washed areas within these lines demonstrate the clinical targets prescribed 60 and 57 Gy, respectively.

(A) Fine-needle aspiration (FNA) biopsy of the left supraclavicular lymph nodes shows sheets of neoplastic tumor cells, with an acute inflammatory infiltrate consistent with anaplastic thyroid carcinoma (ATC). The tumor cells lack conventional papillary thyroid carcinoma (PTC) nuclei and nested or papillary growth pattern and show mitotic activity (arrow; hematoxylin and eosin histology section at 200 × ). (B) Fluorodeoxyglucose (FDG)-positron emission tomography (PET)/computed tomography (CT) at presentation demonstrates a hypermetabolic mass engrossing the midline and left neck from the level of the skull base to the superior mediastinum, with additional hypermetabolic disease in the right lateral neck. (C) Pretreatment axial high-resolution contrast enhanced CT image at the level of the thyroid gland demonstrates a large heterogeneous hypodense mass arising from the left lobe, resulting in tracheal deviation toward the right. The tumor extends posteriorly to involve the tracheoesophageal groove, with direct invasion of the esophagus (black arrow), involvement of the prevertebral soft tissues, and encasement of the vertebral artery (small white arrow). Anteriorly, there is direct invasion of the sternocleidomastoid (large white arrow). (D) Axial CT image at the level of the supraglottis demonstrates 360° encasement of the carotid artery (black arrow). The tumor directly invades the supraglottic larynx and pyriform sinus (large white arrow), and there is anterior extension to involve the strap muscles (curved white arrow). The left internal jugular is occluded, and tumor directly invades the sternocleidomastoid (small white arrow).