Hurthle Cell Tumour - A case of delayed metastatic disease causing abnormal thyroid function, acromegaly and hypercalcaemia
Shoib Ur Rehman, Tom Roques, Jeremy Turner, Ketan Dhatariya, Norfolk and Norwich University Hospital
A 69-year old man presented with a low FT4 (<5pmol/L), normal TSH (1.22mU/L) and FT3 (5.9pmol/L) confirmed on multiple assay platforms. Pituitary testing was consistent with mild biochemical acromegaly [IGF1 29nmol/L, GH suppression nadir 0.92ug/L]. MRI pituitary was normal. He had undergone a right hemi-thyroidectomy in 2001 for a benign thyroid adenoma.
During his current investigations he was found to have a 9.4cm incidental liver mass by the gastroenterologists. Initial biopsy results were consistent with a primary hepatocellular carcinoma. However on review of the histology given his thyroid history the liver lesion was confirmed as metastatic follicular Hurthle cell carcinoma. Immunochemistry for TTF1 was positive and thyroglobulin levels were >30000ng/ml (NR<1). Review of his 2001 thyroid histology also confirmed a Hurthle cell tumour.
His liver mass continued to grow and was deemed too large for surgical removal or ablation. After extensive national discussions it was felt he may benefit from radioiodine therapy after total thyroidectomy. The completion thyroidectomy specimen showed no signs of neoplasia. An I131 uptake scan of the liver mass showed no uptake, compatible with a de-differentiated tumour. The patient then developed severe refractory hypercalcemia resistant to all conventional therapies (fluids, bisphosphonates, denosumab & cinacalcet). He developed cardiac and renal failure and he died 10 months after initial presentation. The family declined necropsy.
This case is unusual because of the abnormal TFT’s – suggesting that the tumour may have been locally de-iodinating fT4, and it may have also produced protein fragments e.g. undetectable PTHRP like molecules causing malignant hypercalcaemia, and biochemical acromegaly.
Hurthle cell tumours constitute up to 5 % of all thyroid neoplasms. They metastasize more frequently than papillary and follicular cancers with an incidence of up to 33%. Fine needle aspiration alone may not be sufficient to differentiate between benign and malignant cells. A critical pathological review of Hurtle cell cancers resulted in diagnostic revision in 28% of cases. These tumours can behave very aggressively, with 5 year mortality rates approaching 80%.