False statement about pheochromocytoma –
**Core Concept**
Pheochromocytoma is a rare, catecholamine-secreting neuroendocrine tumor arising from the adrenal gland, often leading to hypertension, tachycardia, and other systemic symptoms. The tumor's excessive production of catecholamines, such as epinephrine and norepinephrine, is responsible for its clinical manifestations.
**Why the Correct Answer is Right**
Pheochromocytomas are typically benign, although they can be malignant, and are characterized by the unregulated release of catecholamines from the tumor cells. This leads to symptoms such as hypertension, palpitations, sweating, and headaches. The excessive catecholamine production also causes vasoconstriction, which contributes to the development of hypertension. In addition, the tumor's catecholamine secretion can lead to cardiac complications, such as left ventricular hypertrophy and arrhythmias.
**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because pheochromocytomas are not typically associated with hypoglycemia. The excessive catecholamine production leads to hyperglycemia, not hypoglycemia.
**Option B:** Incorrect because pheochromocytomas are not known to be associated with thyroid dysfunction. However, some cases may present with secondary symptoms such as weight loss or palpitations, which can be attributed to the catecholamine excess.
**Option C:** Incorrect because pheochromocytomas are not typically associated with hypercalcemia. However, some cases may present with secondary symptoms such as bone pain or renal calculi, which can be attributed to the catecholamine excess.
**Option D:** Incorrect because pheochromocytomas are not typically associated with hematuria. However, some cases may present with secondary symptoms such as hypertension or cardiac complications, which can be attributed to the catecholamine excess.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that pheochromocytomas can be associated with other tumors, such as von Hippel-Lindau disease, multiple endocrine neoplasia type 2, and neurofibromatosis type 1, which is a classic exam trap.
**Correct Answer: B.**