A 68-year-old woman was referred for 8 month history of a neck lump, dysphonia and unintentional weight loss of 15kg.
Her background included multinodular goitre (MNG) and Hashimoto’s hypothyroidism managed on thyroxine, with subsequent Graves’ disease 8 years later with a Thyrotropin receptor antibody level of 7.9 IU/L. Other history included depression and left arm melanoma excision. Her medications included celecoxib and escitalopram. She did not drink alcohol or smoke and was a carer for her husband. There was no family history of malignancy and no history of neck irradiation.
She had a blood pressure of 110/60mmHg with right neck swelling. Pemberton’s sign was negative. Cardiorespiratory exam was unremarkable.
Ultrasound demonstrated a 23mm soft tissue mass adjacent to the right thyroid. Computed tomography scan showed mass effect of goitre on the trachea and oesophagus with right cervical lymphadenopathy. FDG PET scan demonstrated an intensely avid lobulated right thyroid lobe mass with right neck and mediastinal nodes. Biopsy confirmed medullary carcinoma with positive calcitonin.
Multiple Endocrine Neoplasia screening was negative. Due to the degree of extrathyroidal extension involving the trachea and common carotid artery, this T4aN1bMx medullary thyroid carcinoma (MTC) was not amenable to surgery. Subsequent investigations included a variant of unknown significance in the RET gene. The tissue was NTRK positive and she enrolled in a clinical trial for Larotrectinib. Following the fifth cycle, imaging demonstrated progressive tracheal compression.
Surgical resection is the mainstay of management for MTC(1). Tyrosine Kinase Inhibitors are an option for unresectable disease(2). This case demonstrates a 68 year old female with an unusual background of Hashimoto’s hypothyroidism, subsequent Graves’ disease with concomitant MNG, who presented with Stage 4 unresectable MTC and tolerated a Larotrectinib trial but developed disease progression. The prognosis is poor with a 5-year survival rate of 26% for metastatic disease(3).