A 71-Year-Old Woman with NTRK Gene Fusion Thyroid Cancer

Case: A 71-Year-Old Woman With Thyroid NTRK Gene Fusion Cancer

Initial Presentation

• A 71-year-old woman presents with a painless “ball on his neck”
• PMH: hypercholesterolemia, medically controlled
• PE: palpable, non-tender solitary left-of-the midline neck mass; otherwise unremarkable

Clinical Workup and Initial Treatment

• Labs: including TSH, anti-Tg antibodies WNL
• Ultrasound of the neck revealed a 3.8 cm suspicious mass arising from the left thyroid; 4 suspicious submandibular lymph nodes, largest 2.2 cm in size
• Ultrasound-guided FNAB of the thyroid mass and the largest lymph node confirmed undifferentiated papillary thyroid carcinoma
• Chest/abdominal/pelvic CT showed no evidence of distant metastases
• Patient underwent total thyroidectomy with therapeutic central compartment and left selective neck dissection
  • Pathology: 3.8 cm undifferentiated papillary thyroid cancer arising in left lobe of thyroid, 2 of 7 positive central compartment lymph nodes, largest 1.3 cm, no extra nodal extension
• StageT2N1M1; ECOG PS 0
  
  

Follow-Up and Additional Treatment

• She was treated with radioactive iodine 150 millicuries
  • Whole body scan showed uptake in neck only consistent with thyroid remnant
  • Added levothyroxine to regimen
• Follow-up at 2 months TSH 0.2 mU/L; thyroglobulin 26 ng/mL
  • MRI of the brain revealed multiple small lesions
• Biomarkers testing:NTRK fusion+, RET-, BRAF-, NRAS-,KRAS-
• Initiated treatment with larotrectinib 100 mg PO BID