Abstract
Parathyroid carcinoma is an exceptionally rare endocrine malignancy, accounting for less than 1% of primary hyperparathyroidism cases. Its occurrence in the setting of tertiary hyperparathyroidism secondary to chronic kidney disease is exceedingly uncommon and represents a diagnostic challenge. We report the case of a 37-year-old woman with end-stage renal disease on chronic hemodialysis and a history of hyperprolactinemia, who presented with diffuse bone pain associated with severe hypercalcemia and markedly elevated parathyroid hormone levels. Cervical ultrasonography revealed a left inferior parathyroid lesion measuring 19 × 19 mm. Technetium-99m sestamibi scintigraphy demonstrated pathological uptake corresponding to an orthotopic left inferior parathyroid gland.
Laboratory investigations showed a corrected serum calcium of 2.8 mmol/L and parathyroid hormone (PTH) level of 1203 pg/mL, leading to the diagnosis of tertiary hyperparathyroidism. The patient underwent subtotal parathyroidectomy with identification and dissection of the four pathological parathyroid glands. Intraoperatively, the right inferior gland was noted to be markedly adherent to surrounding tissues. A 7/8 subtotal parathyroidectomy was performed: the left superior, left inferior (carcinomatous), and right inferior (adherent) glands were resected in their entirety, and only half of the right superior gland was left in situ. Postoperative recovery was uneventful under antibiotics and analgesics, and the patient was discharged on postoperative day 3 after drain removal. Definitive histopathological examination revealed a left inferior parathyroid carcinoma, measuring 9 × 6 × 4 mm and weighing 3 g, with histological evidence of capsular invasion and infiltration of the adjacent fibro-adipose tissue, lymphatic invasion, and angioinvasion, associated with nodular hyperplasia of the remaining parathyroid glands. Postoperative laboratory assessment showed normalization of PTH levels to 24 pg/mL and correction of serum calcium to 1.95 mmol/L. Over 2 years of follow-up, PTH levels showed a progressive decline with no evidence of recurrence on serial cervical ultrasonography. Follow-up cervical ultrasonography demonstrated a normal thyroid gland without residual lesion. This case highlights the diagnostic difficulties of parathyroid carcinoma in the context of tertiary hyperparathyroidism and emphasizes the importance of histopathological examination for definitive diagnosis.
Keywords: Parathyroid carcinoma; tertiary hyperparathyroidism; hemodialysis; chronic kidney disease; subtotal parathyroidectomy; hypercalcemia.
