Tongue squamous cell carcinoma producing both parathyroid hormone-related protein and granulocyte colony-stimulating factor: a case report and literature review

Paraneoplastic syndrome generally results from tumor-derived hormones or peptides that cause metabolic derangements. Common metabolic conditions include hyponatremia, hypercalcemia, hypoglycemia, and Cushing's syndrome. Herein, we report a very rare case of tongue carcinoma presenting with leukocytosis and hypercalcemia. A 57-year-old man was admitted to our hospital with tongue squamous cell carcinoma (cT4aN0M0, stage IV). He underwent radical resection following preoperative chemoradiotherapy, but locoregional recurrence was detected 2 months after surgery. He presented with marked leukocytosis and hypercalcemia with elevated serum levels of granulocyte colony-stimulating factor (G-CSF) and parathyroid hormone-related protein (PTHrP). He was therefore managed with intravenous fluids, furosemide, prednisolone, elcatonin, and pamidronate. However, the patient died 1 month later of carcinomatous pleuritis following distant metastasis to the lung. Immunohistochemical analyses of the resected specimens revealed positive staining for PTHrP and G-CSF in the cancer cells. In this case, it was considered that tumor-derived G-CSF and PTHrP caused leukocytosis and hypercalcemia.