Metachronous primary hyperparathyroidism due to a parathyroid adenoma and a subsequent carcinoma: Report of a case

An extremely rare case of metachronous primary hyperparathyroidism (PHP) du e to a parathyroid adenoma and subsequent carcinoma with local lymphatic sp read is presented herein. A 55-year-old woman was operated on for a parathy roid adenoma. in the right inferior gland. Thirteen years after the first o peration, she was again hospitalized for hypercalcemia and the presence of a hard mass in the right anterior neck region. Exploratory surgery and a hi stological examination of the resected tumor provided evidence of a parathy roid neoplasm in the right superior gland but the malignancy was equivocal. Postoperatively, her serum parathyroid hormone (PTH) level remained at 1.5 -fold the upper limit of the normal range, and hypercalcemia again graduall y developed. The results of higher positive rates by Ki-67 immunohistochemi cal staining and an aneuploid pattern by a flow cytometric analysis of the second neoplasm were consistent with a histological diagnosis of carcinoma, and she therefore underwent further surgery. A radical neck dissection rev ealed two lymph node metastases which were both successfully removed. The p ostoperative serum PTH and calcium levels then returned to within the norma l ranges. These findings indicate the usefulness of Ki-67 immunohistochemic al staining and a flow cytometric analysis for differentiating malignant le sions from benign parathyroid lesions, and the importance of surgically tre ating cases limited to local regions without distant metastasis.