Which tumor is associated with paraneoplastic hypercalcemia?

Paraneoplastic hypercalcemia is often associated with certain tumors that produce parathyroid hormone-related peptide (PTHrP), which mimics the action of parathyroid hormone (PTH) and leads to increased calcium levels in the blood. Lung squamous cell carcinoma is a prime example of such a tumor. It is known to secrete PTHrP, resulting in hypercalcemia in affected patients.

In contrast, while other tumors can lead to changes in calcium metabolism or bone density, they typically do not cause hypercalcemia through this mechanism. Medullary thyroid carcinoma is more commonly associated with the production of calcitonin rather than PTHrP. Renal cell carcinoma can lead to calcium abnormalities due to other mechanisms, such as osteolytic bone metastases, but not specifically through paraneoplastic hypercalcemia. Hepatocellular carcinoma does not typically cause hypercalcemia; rather, it can occasionally lead to other metabolic disturbances, but not through the paraneoplastic release of PTHrP.

Thus, lung squamous cell carcinoma is distinctly recognized for its role in paraneoplastic hypercalcemia due to the secretion of PTHrP, making it the correct answer.