Parathyroid carcinomas are rare tumors that arise in the normally located or an ectopic gland. Here, we present a case of a 36-year-old female patient who presented with a history of generalized bone pain, associated with multiple fractures and with elevated serum calcium, parathyroid hormone (PTH) levels, and low vitamin D levels. Biochemical evaluation suggested primary hyperparathyroidism. Initial technetium-99m sestamibi scan and choline 11 scans were misleading and surgical exploration of the neck and superior mediastinum revealed three small parathyroid glands, right superior and inferior, and left superior, all unremarkable on biopsy. Initial surgery failed to alleviate the symptoms. An ectopic parathyroid adenoma was localized in the precarinal space on a gallium 68 DOTANOC PET scan. Repeat surgery by sternotomy, transpericardial approach, and exploration of the mediastinum with intraoperative PTH monitoring was successful in identification and complete excision of parathyroid carcinoma. Operative management of patients with persistent hyperparathyroidism is difficult despite the new advances in radiological imaging. Patients are better managed with a combined approach of biochemical tests, imaging, and intraoperative parathyroid hormone monitoring.