Parathyroid Water-Clear Cell Hyperplasia: Case Report and a Brief Review of the Literature

Parathyroid water-clear cell hyperplasia (WCCH) is an exceptionally rare cause of primary hyperparathyroidism, characterized by the multiglandular replacement of parathyroid tissue by large vacuolated hyperplastic parathyroid cells. Its clinical significance lies in its rarity and the diagnostic difficulties it presents, particularly the frequent failure of preoperative localization studies.

We present a case of a 49-year-old female who presented with an eight-month history of fatigue, nausea, and weakness. Biochemical evaluation revealed mild hypercalcemia with markedly elevated parathyroid hormone (iPTH), consistent with primary hyperparathyroidism. Preoperative neck ultrasound and sestamibi SPECT/CT were equivocal, suggesting possible multiglandular disease without localizing a dominant adenoma. A multidisciplinary tumor board recommended bilateral neck exploration. During the operation, surgeons discovered that each of the four parathyroid glands was enlarged, weighing a combined 31.6 grams. A total parathyroidectomy with forearm autotransplantation was performed. Histopathology confirmed diffuse WCCH. The patient developed transient but severe postoperative "hungry bone syndrome" requiring aggressive supplementation, with eventual normalization of calcium and successful autograft function. At two-year follow-up, she remains normocalcemic and asymptomatic.

This case highlights that WCCH can present with massive glandular enlargement despite only mild-to-moderate biochemical abnormalities. It underscores the unreliability of standard localization imaging for WCCH. It reinforces the essential role of bilateral neck exploration as the definitive diagnostic and therapeutic procedure when multiglandular disease is suspected.