Abstract Introduction Primary hyperparathyroidism is usually caused by parathyroid adenomas, however atypical tumors are rare. Brown tumors can occur from excessive parathyroid hormone release, which increases osteoclastic bone resorption. Although rare, atypical parathyroid tumors can cause such lesions. An unusual parathyroid tumor with a brown tumor is shown here. Clinical Case A 57-year-old woman presented to the orthopedics clinic with complaints of left hip pain. Imaging revealed a mass in the left acetabulum. Laboratory tests suggested primary hyperparathyroidism, and she was referred to endocrinology with a suspected brown tumor. Left hip pain had been present for 1.5 years, with recent worsening, causing difficulty in walking. Her medical history included percutaneous nephrolithotripsy for nephrolithiasis. Physical examination revealed painful and restricted movements of the left hip. Laboratory investigations demonstrated: calcium 13.2 mg/dL (8.8–10.6), phosphorus 2.2 mg/dL (2.5–4.5), PTH 883 ng/L (15–65), 25-OH vitamin D 35.2 μg/L, creatinine 1.05 mg/dL (0–1.2), TSH 0.8 mUI/L (0.48–4.81), and 24-hour urinary calcium 312 mg/day (0–300). Neck ultrasonography showed a 30x15 mm hypoechoic solid nodule posterior to the left thyroid lobe, suggestive of a parathyroid adenoma, along with additional hypoechoic solid nodules measuring 25 x 10 mm at the left lobe–isthmus junction and 17x10 mm within the left lobe, which were evaluated as thyroid nodules. Parathyroid scintigraphy confirmed the suspected parathyroid lesion. Thyroid scintigraphy showed that the nodules in the left lobe had a hyperfunctioning pattern. Pelvic MRI revealed a heterogeneous mass measuring 8x5 cm, eroding almost the entire acetabulum. Bone mineral densitometry indicated severe osteoporosis (L1–L4 T-score: –3.9; femoral neck T-score: –4.2). Ultrasound showed multiple calculi in the lower pole of the left kidney, the largest 5 mm. The patient was hospitalized, started on intravenous hydration, and given zoledronic acid. She then underwent left hemithyroidectomy and left inferior parathyroidectomy. Histopathological examination of the thyroid specimen revealed follicular nodular disease. The parathyroid specimen showed irregular parathyroid parenchyma with nodular hyperplasia, and the differential diagnosis included atypical parathyroid tumor and prior biopsy tract changes. However, the patient had no history of invasive neck procedures. Postoperatively, serum calcium and PTH normalized. The patient was closely monitored for atypical parathyroid tumor, and orthopedic follow-up was planned for the brown tumor. Conclusion This case shows a rare presentation of an atypical parathyroid tumor with a destructive brown tumor in the acetabulum. Clinicians should strongly suspect primary hyperparathyroidism in patients with unexplained osteolytic lesions, especially if labs show hypercalcemia and high PTH.
Karataş et al. (Thu,) studied this question.