Introduction: Atypical parathyroid adenoma (APA) constitutes approximately 0.5–4.0% of all cases of primary hyperparathyroidism (pHPT). Here, we report a case of APA presenting with severe hypercalcemia, complicated with renal impairment, bilateral medullary nephrocalcinosis, and multiple fragility fractures. Case: A 45-year-old male initially presented with a 6-month history of constipation, polyuria, lethargy, bone pain, and difficulty in initiating micturition. Laboratory investigations revealed impaired renal function with an estimated glomerular filtration rate of 41.4 mL/min, severe hypercalcemia (4.07 mmol/L), and an elevated intact parathyroid hormone (iPTH) level of 104.0 pmol/L (reference range: 1.58–6.03 pmol/L), confirming the diagnosis of pHPT. He was also found to have vitamin D deficiency, with a serum total 25-hydroxyvitamin D level of 46 nmol/L. Ultrasound of the abdomen demonstrated bilateral medullary nephrocalcinosis, while neck ultrasound and Tc-99 m sestamibi parathyroid scintigraphy revealed a concordant lesion in the posterior aspect of the left thyroid lobe, suggestive of a parathyroid adenoma. He returned 3 months later with closed fractures of the right subtrochanteric femur and the right humerus following a fall from standing height. In view of persistent hypercalcemia despite hyperhydration and treatment with zoledronic acid, subcutaneous denosumab (60 mg) was administered, resulting in an improvement in serum calcium levels. A left inferior parathyroidectomy was then performed concurrently with internal fixation of the right femur. The surgery was uneventful. Histopathological examination confirmed an atypical parathyroid adenoma. Postoperatively, the serum calcium and iPTH levels normalized, and the patient remained asymptomatic and normocalcemic during regular follow-up. Conclusion APA remains a diagnostic and therapeutic challenge due to its clinical, biochemical, and histopathological features of equivocal malignancy. Surgical resection remains the mainstay of management of APA, and long-term surveillance is essential in view of its uncertain malignant potential and risk of recurrence.
Hypercalcemia ; Parathyroid Neoplasms