**Core Concept**
Cushing syndrome is a rare endocrine disorder caused by excessive exposure to cortisol, a hormone produced by the adrenal gland. This can be due to various reasons such as a pituitary tumor, adrenal tumor, or exogenous steroid use. The excess cortisol leads to various clinical manifestations including weight gain, hypertension, and glucose intolerance.

**Why the Correct Answer is Right**
The correct answer is related to the pathophysiology of Cushing syndrome. The primary cause of Cushing syndrome is the overproduction of adrenocorticotropic hormone (ACTH) by the pituitary gland, which stimulates the adrenal gland to produce excessive cortisol. This can be due to a pituitary tumor (adenoma) that secretes ACTH autonomously. Other causes include adrenal tumors that produce cortisol autonomously or exogenous steroid use.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not specify a condition that is not associated with Cushing syndrome. We need more information to evaluate this option.
**Option B:** This option is incorrect because it is a characteristic of Cushing syndrome, not a condition that is not associated with it. Excessive weight gain and hypertension are common manifestations of Cushing syndrome.
**Option C:** This option is incorrect because it is a condition that can cause Cushing syndrome, not a condition that is not associated with it. Adrenal tumors can produce cortisol autonomously, leading to Cushing syndrome.

**Clinical Pearl / High-Yield Fact**
A classic exam trap in Cushing syndrome is to remember the "7 Ps":

* Purple striae
* Poor wound healing
* Polyuria
* Polydipsia
* Psychiatric symptoms
* Proximal muscle weakness
* Purplish coloration of the face

**Correct Answer:**