Spontaneous hemorrhage from a functionally well-controlled, non-enlarged but hyperplastic parathyroid gland due to secondary hyperparathyroidism: a case report.

Chronic kidney disease causes secondary hyperparathyroidism (SHPT) with hyperplastic enlarged parathyroid glands. Deep cervical spontaneous hemorrhage has been occasionally reported to be caused by rupture of an enlarged parathyroid gland under functionally uncontrolled SHPT. We encountered an unusual case of life-threatening spontaneous hemorrhage from a parathyroid gland in a patient undergoing hemodialysis. A 40-year-old man with end-stage renal disease received renal replacement therapy for 12 years. He had SHPT, which was functionally well controlled using multiple medications. The parathyroid glands had not been reported to be enlarged. He presented with sudden-onset progressive cervical swelling and pain without any specific triggers. Computed tomography revealed hematoma formation around the thyroid gland and in the upper mediastinum, as well as a clearly defined high-density mass shadow on the right dorsal surface of the thyroid gland. Therefore, the patient was diagnosed with parathyroid gland hemorrhage. The next day, emergency surgery was performed because the hematoma had expanded and his clinical symptoms had worsened. Pathology revealed that the excised right lower parathyroid gland measured 7 mm, was non-enlarged, and comprised hyperplastic parathyroid tissue with hemorrhage. Our report indicates that severe parathyroid gland hemorrhage can occur even in functionally well-controlled SHPT with hyperplastic but non-enlarged parathyroid glands. Because spontaneous parathyroid gland hemorrhage may be linked to a relative imbalance between parathyroid gland cell growth and blood supply, regular evaluation of blood flow and the parathyroid glands using ultrasonography is important in patients with SHPT.