A Case of no Obvious Parathyroid Adenoma Revealed by Preoperative Image Diagnosis in a Postmenopausal Woman with Breast Cancer Receiving an Adjuvant Aromatase Inhibitor

Abstract

The patient was a 71-year-old woman who had been diagnosed as having breast cancer, and then received left total mastectomy + sentinel lymph node dissection in another hospital three years previously. Postoperatively, she received adjuvant chemotherapy for one year, followed by administration of an aromatase inhibitor and a bisphosphonate, two years previously. She had continued to have hypercalcemia since before breast surgery. She was referred to our department by an internal physician in our hospital for evaluation of multiple nodular goiter. Laboratory analysis revealed hypercalcemia (10.4mg/dl) and high serum intact-PTH level (137pg/ml). The bone mineral density of the young adult mean of the lumbar spine was 55%. Hyperparathyroidism was suspected. Ultrasonography of the neck and contrast-enhanced CT findings revealed almost no parathyroid adenoma in the right thyroid lobe, and 99mTc-sestamibi scintigraphy revealed a nodule with increased radiotracer uptake only in the right thyroid lobe suggestive of the intrathyroidal parathyroid adenoma. Considering intrathyroidal parathyroid adenoma in the right thyroid lobe or small parathyroid adenoma, right hemithyroidectomy and exploratory parathyroidectomy were performed following identification of the dissection area. Histopathology of the right superior and right inferior parathyroid glands revealed normal parathyroid gland and left inferior parathyroid gland was a parathyroid adenoma measuring 0.8cm in diameter with 1-2mm thick. Histopathology of the intrathyroidal tumor revealed follicular adenoma in the thyroid gland. We should perform exploratory parathyroidectomy intraoperatively in order to prevent osteoporosis developing easily in postmenopausal women with breast cancer receiving an adjuvant aromatase inhibitor associated with primary hyperparathyroidism, even if it is difficult to identify the location of no obvious parathyroid adenoma by preoperative imaging.