Recurrent erythematous plaques on glans penis in a 19 yrs old sexually active male which heals with residual hyperpigmentation, is suggestive of?
**Recurrent Erythematous Plaques on Glans Penis**
**Core Concept**
The condition described is a classic example of an autoimmune bullous disease, specifically a form of **lichen planus**, which is a chronic inflammatory condition affecting the skin and mucous membranes. Lichen planus is characterized by the presence of **T lymphocytes** and **antigen-presenting cells** that trigger an immune response, leading to the formation of bullae and subsequent scarring.
**Why the Correct Answer is Right**
The clinical presentation of recurrent erythematous plaques on the glans penis, which heal with residual hyperpigmentation, is highly suggestive of lichen planus. This condition often presents with ** Wickham's striae**, which are fine white lines or a reticular pattern seen on the surface of the lesions. The presence of these striae, along with the characteristic clinical features, helps to differentiate lichen planus from other conditions such as contact dermatitis or psoriasis.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because **fixed drug eruption** typically presents with well-demarcated, circular lesions that develop at the site of drug exposure, without the characteristic Wickham's striae or residual hyperpigmentation.
**Option B:** This option is incorrect because **psoriasis** typically presents with erythematous, scaly plaques, and not with the characteristic residual hyperpigmentation seen in lichen planus.
**Option C:** This option is incorrect because **erythema multiforme** typically presents with target lesions, which are concentric rings of color, and not with the characteristic Wickham's striae or residual hyperpigmentation seen in lichen planus.
**Clinical Pearl / High-Yield Fact**
Lichen planus can affect the mucous membranes, including the oral cavity, and can be associated with **oral lichen planus**, which is a significant risk factor for the development of **oral squamous cell carcinoma**.
**Correct Answer: C. Lichen planus**