Dennie Morgan fold is seen in
**Core Concept**
The Dennie-Morgan fold is a clinical sign associated with allergic rhinitis, characterized by a skin fold or crease below the lower eyelid. This sign is a result of chronic rubbing and itching of the eyes due to allergic inflammation.
**Why the Correct Answer is Right**
The Dennie-Morgan fold is a physical manifestation of atopic dermatitis or allergic rhinitis, where the skin beneath the lower eyelid becomes thickened and folded due to repeated rubbing and scratching. This is a result of the release of histamine and other chemical mediators during an allergic reaction, leading to increased vascular permeability and edema. The presence of a Dennie-Morgan fold is often used as a diagnostic clue in patients presenting with symptoms of allergic rhinitis.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect as the Dennie-Morgan fold is not typically associated with thyroid eye disease, which presents with proptosis, eyelid retraction, and edema of the eyelids.
**Option B:** This option is incorrect as the Dennie-Morgan fold is not a characteristic feature of conjunctivitis, which presents with redness, discharge, and swelling of the conjunctiva.
**Option C:** This option is incorrect as the Dennie-Morgan fold is not a feature of blepharospasm, which presents with involuntary spasms of the eyelid muscles.
**Clinical Pearl / High-Yield Fact**
The Dennie-Morgan fold is a useful clinical sign to identify patients with allergic rhinitis, and its presence can guide the physician to investigate for other atopic conditions such as asthma and atopic dermatitis.
**Correct Answer: A. Allergic rhinitis.**