Sarcoidosis Lymph Node Mimicking a Cervical Parathyroid Adenoma on 99m-Tc Sestamibi Imaging

Abstract A 70-year-old woman presented to our department with hypercalcemia. Laboratory tests revealed elevated parathyroid hormone levels at 335 pg/mL, while vitamin D 25-OH levels were normal at 26 ng/mL. Based on these findings, primary hyperparathyroidism was suspected. A neck ultrasound revealed a 12-mm mass near the lower pole of the left thyroid lobe, and a subsequent 99m-TcMIBI (technetium-99m sestamibi) scan confirmed increased uptake in the same area, suggesting a left inferior parathyroid adenoma. Given the concordance between the ultrasound and MIBI scan results, the patient underwent surgical exploration. Unexpectedly, the histopathological report identified a lymph node formation containing monomorphous epithelioid granulomas, suggestive of sarcoidosis. Through this interesting case, the authors highlight the importance of considering sarcoidosis in the differential diagnosis of hypercalcemia, especially when imaging findings suggest a parathyroid adenoma, as sarcoidosis can mimic such an adenoma in isolated cervical lymph nodes.