Cutaneous Squamous Cell Carcinoma Producing Granulocyte Colony-stimulating Factor and Parathyroid Hormone-related Protein: A Case Report and Literature Review.

We herein report a case of cutaneous squamous cell carcinoma (SCC) characterized by paraneoplastic hypercalcemia-leukocytosis syndrome. The patient presented with systemic symptoms, including anorexia, a fever, and a tumoral lesion on the upper arm. Laboratory test results revealed hypercalcemia and leukocytosis. A tissue biopsy confirmed SCC, and further investigation revealed elevated parathyroid hormone-related protein (PTHrP) and granulocyte-colony stimulating factor (G-CSF) levels. Immunostaining demonstrated G-CSF production by the tumor cells. Radiation therapy was administered, which improved leukocytosis and decreased G-CSF and PTHrP levels. Through a case report and literature review, we explored the clinical characteristics of tumors that produce G-CSF and PTHrP.