**Question:** Acanthosis nigricans is seen in -

A. Diabetes mellitus
B. Obesity
C. Hyperprolactinemia
D. Acromegaly

**Core Concept:** Acanthosis nigricans is a skin condition characterized by the development of dark, velvety, thickened skin, typically on the neck, axillae, and groin. It is a clinical sign that can indicate various underlying conditions.

**Why the Correct Answer is Right:** Acanthosis nigricans is a clinical manifestation resulting from hormonal imbalances, particularly insulin resistance and hyperinsulinemia. It is commonly associated with insulin-secreting tumors such as acromegaly or Cushing's disease. In this case, acanthosis nigricans is a consequence of the elevated insulin and growth hormone levels.

**Why Each Wrong Option is Incorrect:**

A. Diabetes mellitus: Acanthosis nigricans can be seen in type 2 diabetes, but it is not a typical feature of type 1 diabetes. Type 1 diabetes is associated with ketoacidosis, not acanthosis nigricans.

B. Obesity: Acanthosis nigricans can be seen in obese patients due to hormonal changes, but it is not specific to obesity alone. Obesity is more likely if the acanthosis nigricans is associated with insulin resistance or hyperinsulinemia.

C. Hyperprolactinemia: While acanthosis nigricans can manifest in hyperprolactinemia, it is less common and often associated with other hormonal irregularities like Cushing's disease or acromegaly.

**Clinical Pearl:** The correct association of acanthosis nigricans is with conditions like acromegaly and Cushing's disease, which lead to insulin resistance and hyperinsulinemia. In these cases, acanthosis nigricans serves as a clue to the underlying hormonal disorder.

**Correct Answer:** D. Acromegaly. Acanthosis nigricans is a clinical sign often seen in patients with acromegaly, a hormonal disorder characterized by excessive growth hormone production. This condition is associated with insulin resistance and hyperinsulinemia, leading to the development of acanthosis nigricans.