**Question:** Acanthosis nigricans is associated with malignancies and: March 2013

**Core Concept:**
Acanthosis nigricans is a dermatological condition characterized by the development of hyperpigmented, thickened, and velvety papules, typically affecting the axillae, neck, and groin regions. It is commonly seen as a cutaneous manifestation of endocrinopathies, such as insulin resistance, and can also be associated with malignancies.

**Why the Correct Answer is Right:**
The correct answer, D, refers to the association between acanthosis nigricans and malignancies. Acanthosis nigricans is a clinical sign that can indicate the presence of an underlying malignancy, particularly in cases where acanthosis nigricans is diffuse and non-responsive to treatment for the known endocrinopathies.

**Why Each Wrong Option is Incorrect:**
A, B, and C are incorrect because they refer to specific endocrinopathies associated with acanthosis nigricans, rather than malignancies. These include:

A. Insulin resistance: A common cause of acanthosis nigricans, but not the malignancy itself.
B. Hyperthyroidism: Another endocrinopathy that can lead to acanthosis nigricans but does not directly represent a malignancy.
C. Cushing's syndrome: A hormonal disorder causing acanthosis nigricans, not a malignancy.

**Clinical Pearl:**
Acanthosis nigricans should prompt a thorough clinical evaluation for the presence of an underlying malignancy. While insulin resistance and other endocrinopathies can cause acanthosis nigricans, it is essential to consider malignancies such as pancreatic, gastrointestinal, or ovarian tumors, as these can be life-threatening if diagnosed late.

**Correct Answer:** D (malignancy)