Perioral pigmentation and Dennie-Morgan sign are seen in the following condition:
**Core Concept**
Atopic dermatitis, also known as eczema, is a chronic inflammatory skin condition characterized by dry, itchy, and scaly skin. It often presents with specific physical signs and symptoms that aid in diagnosis.
**Why the Correct Answer is Right**
The presence of perioral pigmentation and Dennie-Morgan sign are characteristic features of atopic dermatitis. Perioral pigmentation refers to the darkening of skin around the mouth, while Dennie-Morgan sign is the presence of a fold of skin under the lower eyelid. These signs are due to chronic inflammation and skin barrier disruption in atopic dermatitis. The exact mechanisms involve the release of pro-inflammatory cytokines, such as IL-4 and IL-13, which contribute to skin thickening and hyperpigmentation.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because atopic dermatitis is not primarily associated with perioral pigmentation or Dennie-Morgan sign. While skin thickening and hyperpigmentation can occur in atopic dermatitis, they are not the primary features.
* **Option B:** This option is incorrect because contact dermatitis is a type of skin inflammation caused by exposure to allergens or irritants, which typically presents with acute symptoms rather than chronic signs like perioral pigmentation and Dennie-Morgan sign.
* **Option C:** This option is incorrect because psoriasis is a distinct autoimmune skin condition characterized by thick, scaly plaques, which are not typically associated with perioral pigmentation or Dennie-Morgan sign.
**Clinical Pearl / High-Yield Fact**
Dennie-Morgan sign is a useful clinical marker for atopic dermatitis, but it can also be seen in other conditions, such as allergic rhinitis and conjunctivitis. It is essential to consider the overall clinical context and other signs and symptoms when evaluating patients.
**Correct Answer:** C.