A 30-year-old male visited another hospital with dyspnea, polydipsia, and polyuria, as well as vomiting and joint pain, and had experienced weight loss of 25 kg during the previous year. Laboratory testing showed serum calcium at 20.6 mg/dL and PTH elevated to 10,380 pg/mL, and parathyroid cancer was strongly suspected after imaging was performed. The patient was referred to our hospital, where en bloc resection of the tumor located along the left lobe of the thyroid gland and neck dissection were performed, and pathological findings confirmed a diagnosis of parathyroid cancer. Following surgery, radiation therapy with 66 Gy was performed. Thereafter, PTH was 100 pg/mL and the patient was followed in an outpatient setting.
At 32 months after surgery, blood test results showed re-elevation of PTH, and chest computerized tomography (CT) revealed bilateral multiple lung nodules and left pleural dissemination. Symptoms of hypercalcemia also progressed, thus the patient required hospitalization because of progression of subjective symptoms. Treatments for hypercalcemia with intravenous hydration, diuretics, and administration of cinacalcet (a second-generation calcimimetic), as well as denosumab (fully human monoclonal antibody that binds the cytokine receptor activator of NFκB ligand), octreotide (long-acting somatostatin analogue), and zoledronic acid (bisphosphonate) were performed. However, elevation of PTH level and hypercalcemia progressed. Chest X-ray findings showed massive pleural effusion (Fig. 1A). Results obtained with both 99mTc-methoxyisobutylisonitrile (MIBI) scintigraphy and somatostatin receptor scintigraphy revealed functionally active status lesions in left pleural dissemination, but not in the area of pulmonary metastasis (Fig. 1B, C). Radiation therapy with 60 Gy for left pleural dissemination was performed, though response was poor. The patient was then referred to our department for surgical resection of left pleural dissemination at 37 months after the initial surgery.
Volume reduction of left pleural dissemination to control hypercalcemia was performed via 5th intercostal space thoracotomy. There were several hypervascular tumors 3–5 cm in size disseminated throughout the left thoracic cavity, which were resected as much as possible (Fig. 2A, B). The operation duration was 240 minutes and blood loss was 3100 mL. Chest CT results after resection showed that the functionally active site of left pleural dissemination was nearly completely excised (Fig. 2C). PTH level was 46,800 pg/mL prior to resection of pleural dissemination and then decreased to 7,636 pg/mL on the first postoperative day. Infusion volume was gradually decreased and the serum calcium level did not increase. Hypercalcemia symptoms were improved and the patient was discharged 56 days later. Under medical treatment for hypercalcemia with denosumab and cinacalcet, the PTH level gradually increased, while serum calcium level did not change. Eight months after the resection of pleural dissemination, the patient died at home from cachexia related to the disease.