Case presentation

A 75-year-old female with a history of cholecystectomy, nephrolithiasis, and chronic kidney disease presented to the emergency department with acute-onset palpitations and chest pain radiating to the left arm. In the emergency department, the patient was found to have a body mass index of 13, attributed to malnutrition, and was hypertensive and bradycardic. Initial labs revealed significant hypercalcemia to 14.2 mg/dl and elevated PTH to 719 pg/ml. Electrocardiogram was concerning for STEMI, but subsequent urgent cardiac catheterization demonstrated no coronary obstruction. Imaging revealed a 0.7 cm left proximal ureteropelvic junction stone with severe left hydronephrosis and multiple right renal calculi with moderate hydronephrosis. The patient was treated with normal saline for the symptomatic hypercalcemia. A Tc-99 m sestamibi scan was performed, demonstrating a large left-sided parathyroid adenoma (Fig. 1).

Figure 1: (A) Increased immediate areas of uptake in the region of the left thyroid in the 20-minute images. (B) No washout in 3-hour delayed images, suggestive of left parathyroid adenoma.

The patient underwent successful inpatient parathyroidectomy. Intraoperatively, the large parathyroid mass was identified near subclavian vessels and required meticulous dissection during resection (Fig. 2). Intraoperative PTH level at the beginning of the surgery was 1745 pg/ml. A 40-g, 6.5 cm by 5 cm by 4 cm large parathyroid mass was then excised. PTH levels dropped to 365 pg/ml within 10 minutes.

Figure 2: Intraoperative image of parathyroid gland after excision.

Final in-house pathology demonstrated large encapsulated parathyroid tissue, consistent with parathyroid adenoma. Postoperative labs showed normalization of calcium and PTH within six hours. The patient was discharged three days after surgery with calcium supplementation.

The patient presented to the hospital 2 weeks after surgery with symptomatic hypocalcemia and an elevated PTH of 151, which continued to remain elevated despite calcium supplementation. Due to concern for malignancy, outside expert pathologic consultation was obtained, which showed a well-circumscribed parathyroid neoplasm with dense fibrous bands and focal nuclear atypia (Fig. 3). However, there was no evidence of capsular invasion with extension into adjacent soft tissue, no vascular or lymphatic invasion, no perineural invasion, and no metastatic disease identified. Immunohistochemical analysis demonstrated a Ki-67 proliferation index of five percent with retained parafibromin expression. The parathyroid mass was determined to be an atypical parathyroid tumor.

Figure 3: (A) Patient’s parathyroid gland demonstrating nuclear atypia, a feature commonly seen in parathyroid carcinoma. (B) Parathyroid gland demonstrating broad fibrous bands, another feature associated with parathyroid carcinoma. (C) Parathyroid gland demonstrating intact capsule with no invasion, thus lacking the diagnostic feature of parathyroid carcinoma.