Which type of lung cancer is associated with hypercalcemia due to PTH-rp?

• A. Small cell carcinoma
• B. Squamous cell carcinoma
• C. Adenocarcinoma
• D. Large cell carcinoma

Answer: (B)

Squamous cell carcinoma of the lung is specifically associated with hypercalcemia due to the production of parathyroid hormone-related peptide (PTH-rp). This condition arises because PTH-rp mimics the action of parathyroid hormone, leading to an increase in bone resorption and renal tubular reabsorption of calcium, which causes elevated calcium levels in the blood.

This relationship is significant in clinical settings, as hypercalcemia can lead to a range of symptoms, including weakness, confusion, and renal issues, and is often a marker of the malignancy's presence. Squamous cell carcinoma is the lung cancer subtype most commonly linked to this paraneoplastic syndrome. In contrast, other types of lung cancer, such as small cell, adenocarcinoma, and large cell carcinomas, do not typically produce PTH-rp, and thus hypercalcemia is less frequently observed in those cases.