Atypical presentation of oncocytic parathyroid adenoma masquerading as metastatic carcinoma

Abstract

Parathyroid carcinoma is the rarest endocrine malignancy. Definitive diagnosis is challenging as it is difficult to distinguish malignant from benign disease. A 71-year-old man presented with weight loss and hypercalcaemia. CT scans revealed multiple lung nodules and lytic bone lesions that were consistent with metastatic dissemination. Technetium-99m-sestamibi-single-photon emission computed tomography scan showed an abnormal uptake in the right thyroid lobe. Fine-needle aspiration (FNA) was performed on three occasions. The patient underwent parathyroidectomy with ipsilateral hemithyroidectomy without postoperative complications. Microscopic examination showed a parathyroid neoplasm with fibrosis and intravascular tumour on a background of unremarkable thyroid parenchyma. This resulted in an initial impression of parathyroid carcinoma. Further review by two independent pathologists provided a final diagnosis of oncocytic parathyroid adenoma. This case highlights the subjectivity and interobserver variation with endocrine histological examination. FNA can induce changes that mimic parathyroid carcinoma on histology. An index of suspicion for benign parathyroid adenomas should be maintained.

Tertiary hyperparathyroidism masking an atypical parathyroid tumor

“…En bloc resection with ipsilateral thyroid lobectomy is the gold standard in patients with suspected parathyroid carcinoma. 15 Taking into account the high suspicion of malignancy and the setting of THPT in our patient total parathyroidectomy with autotransplantation thus en block right lobectomy was performed.…”

“…The macroscopic appearance at surgery is of limited help; however, firm and adherence to the adjacent structural lesions should raise the suspicion for malignancy and may dictate a more radical surgical approach. En bloc resection with ipsilateral thyroid lobectomy is considered the gold standard in patients with suspected parathyroid carcinoma 15 . Taking into account the high suspicion of malignancy and the setting of THPT in our patient total parathyroidectomy with autotransplantation thus en block right lobectomy was performed.…”