Case:
A 73-year-old woman with parathyroid hormone (PTH)-dependent hypercalcaemia (serum adjusted calcium 3.21mmol/L, PTH 37.5pmol/L) with sonographic features suggestive of a parathyroid adenoma underwent a right inferior parathyroidectomy. At the time of surgery, she was fully independent. Past history included follicular lymphoma under observation, previously treated breast cancer and COPD. Histology was in keeping with a parathyroid adenoma however identified areas of atypical cells and necrosis with absent PTH staining. A calcitonin level was 377ng/L. Subsequent thyroid ultrasound and fine needle aspirate demonstrated epithelioid cells with mild nuclear enlargement and calcitonin positive cells. Two months later she underwent a total thyroidectomy with lymph node dissection identifying bilateral medullary thyroid carcinoma (MTC ) with metastasis to the contralateral central neck nodes and ipsilateral parathyroid gland. Calcitonin level one month post-operatively was markedly elevated at 1388ng/L.
She was hospitalised two months later for functional decline with severe hypocalcaemia (calcium 1.90mmol/L and PTH 3pmol/L) requiring intravenous calcium gluconate plus oral calcium carbonate and calcitriol. A whole-body CT and DOTATATE PET identified new lesions within the axial skeleton, lungs, and adrenal glands. An MRI brain demonstrated multiple intracranial and calvarial lesions. A T12 vertebral body biopsy confirmed metastatic MTC. Although planned for oncology follow up to discuss treatment and genetic testing, she developed respiratory failure and was transitioned to supportive care, passing away 6 months from the initial presentation.
Discussion:
Traditionally MTC has been associated with high mortality rates(1), although this may change with the increasing availability of targeted therapy using multikinase inhibitors (2), highlighting the importance of early detection to facilitate genetic evaluation. Genetic testing for this patient’s family members remains under consideration. Given the potential for rapid progression, diagnosing MTC requires a high degree of clinical suspicion and involvement of multidisciplinary teams when faced with atypical histological findings for presumed benign lesions.