PTHrP-producing Lung Cancer with Symptomatic Hypercalcemia: a Case Report

<p>Background. Hypercalcemia is one of the paraneoplastic syndromes. Because most lung cancer patients with symptomatic hypercalcemia have advanced-stage lung cancer, few patients are resectable and have the chance to receive lung resection. We report the case of a patient who underwent left lower lobectomy for lung cancer after presenting with a loss of appetite and fatigue due to hypercalcemia. Case. An 82-year-old male former smoker presented with left pulmonary tumor on chest X-ray. Computed tomography showed a 7.6-cm tumor with cavities in the left lower lobe. Following a transbronchial biopsy and imaging examination, the patient was diagnosed with stage IIIA lung squamous cell carcinoma in his left lower lobe. He had a loss of appetite before surgery and a blood test indicated hypercalcemia, high parathyroid hormone-related protein (PTHrP), and low intact parathyroid hormone (PTH). The patient was diagnosed with paraneoplastic syndrome due to lung cancer of the left lower lobe. Thoracoscopic left lower lobectomy was performed. Serum calcium rapidly improved to within the normal range after surgery. Subsequently, the patient's appetite and fatigue improved. He was discharged from the hospital on postoperative day 7 with no complications. During follow-up, serology testing revealed that the serum calcium level was within the normal range, and that PTHrP decreased and was also within the normal range. Pathological testing of the resected tumor confirmed the diagnosis as a pT4N0M0 stage IIIA keratinizing squamous cell carcinoma and immunohistochemical staining showed that the specimen was partially positive for PTHrP. Conclusion. Resection should be considered for patients with PTHrP-producing lung cancer with hypercalcemia. The findings from our case indicated that hypercalcemia can be expected to rapidly improve after tumor resection.</p>