Following malignancies most frequently cause hypercalemia except –
**Core Concept**
Hypercalcemia is a condition characterized by elevated calcium levels in the blood, which can be caused by various malignancies through different mechanisms. Paraneoplastic syndromes, tumor cell invasion, and hormone secretion by tumors can lead to hypercalcemia.
**Why the Correct Answer is Right**
Among the malignancies that cause hypercalcemia, breast cancer is a notable exception. Breast cancer often causes hypercalcemia through the secretion of parathyroid hormone-related protein (PTHrP), which acts similarly to parathyroid hormone (PTH) to increase calcium levels. However, this is not the correct answer as it is asked which malignancy does not frequently cause hypercalcemia.
**Why Each Wrong Option is Incorrect**
* **Option A:** Lung cancer, particularly small cell carcinoma, frequently causes hypercalcemia through the secretion of PTHrP or other mechanisms.
* **Option B:** Multiple myeloma is a malignancy that commonly leads to hypercalcemia due to bone destruction and the release of calcium into the bloodstream.
* **Option C:** Squamous cell carcinoma of the head and neck, such as nasopharyngeal carcinoma, can also cause hypercalcemia through PTHrP secretion.
**Clinical Pearl / High-Yield Fact**
It is essential to remember that hypercalcemia can be caused by various malignancies through different mechanisms, including paraneoplastic syndromes, tumor cell invasion, and hormone secretion.
**Correct Answer:** D.