**Core Concept**
Stemmer's sign and buffalo hump are clinical manifestations associated with Cushing's syndrome, a condition characterized by excessive exposure to cortisol due to various etiologies. This excess cortisol can lead to various physical and metabolic changes.

**Why the Correct Answer is Right**
Cushing's syndrome is caused by an excess of cortisol, which can result from an adrenal gland tumor, a pituitary tumor, or long-term use of corticosteroid medications. The excess cortisol causes fat redistribution, leading to the formation of a buffalo hump in the upper back and a loss of fat in the face and arms. Stemmer's sign, a decrease in skin fold thickness, is a result of the same fat redistribution process. The increased cortisol levels also lead to skin changes, such as thinning and fragility.

**Why Each Wrong Option is Incorrect**
**Option A:** This is incorrect as Stemmer's sign and buffalo hump are not features of acromegaly, a condition caused by excess growth hormone.
**Option B:** This is incorrect as these signs are not characteristic of hypothyroidism, a condition caused by insufficient thyroid hormone production.
**Option C:** This is incorrect as these signs are not features of hyperparathyroidism, a condition caused by excess parathyroid hormone production.

**Clinical Pearl / High-Yield Fact**
Remember that Cushing's syndrome can be caused by an adrenal or pituitary tumor, and its diagnosis often requires a combination of clinical findings, laboratory tests, and imaging studies.

**Correct Answer:** C. Cushing's syndrome