[Parapharyngeal salivary gland oncocytoma showing intense radiopharmaceutical accumulation identified during the evaluation of primary hyperparathyroidism by scintigraphy accompanied with SPECT/CT and its transoral endoscope-assisted removal].

Technetium-99m-MIBI (methoxy-isobutyl-isonitrile) is a radiopharmaceutical agent used in the evaluation of myocardial perfusion and parathyroid pathologies. MIBI scintigraphy is a commonly applied diagnostic method in the assessment of parathyroid adenomas for lesion localization and to exclude the presence of ectopic adenomas. However, tracer uptake may also occur in thyroid adenomas, thyroid carcinomas, and other lesions with high mitochondrial density. In our study, we present the case of a 79-year-old female patient. The patient had been under endocrinological care since 1997 due to osteoporosis. Since late 2023, intermittent hypercalcemia accompanied by elevated parathyroid hormone levels has been consistent with a diagnosis of primary hyperparathyroidism. Neck ultrasound and parathyroid scintigraphy with SPECT/CT confirmed an abnormality suggestive of an adenoma of the left superior parathyroid gland, and there was also an intense isotope accumulation in the left retro/parapharyngeal region, suggesting the possibility of malignancy. Based on MRI, the parapharyngeal lesion was not suspected to be malignant. During surgical exploration, the adenoma of the left lower parathyroid gland and the lesion located in the parapharyngeal space were removed, the latter using a minimally invasive, transoral endoscope-assisted technique. Histology confirmed parathyroid adenoma and salivary gland oncocytoma. This case highlights the importance of parathyroid scintigraphy with SPECT/CT in the localization of parathyroid adenomas and that increased isotope accumulation does not always indicate a parathyroid abnormality. Orv Hetil. 2026; 167(9): 351-358.