A young 8 years old boy with multiple, small, pin point, shiny, papular lesions on dorsal aspect of hand, forearms and his penis also. Diagnosis is:
**Core Concept**
Lichen nitidus is a rare, benign skin condition characterized by small, shiny, papular lesions, typically affecting the face, neck, and extremities. It is often misdiagnosed due to its resemblance to other skin conditions, such as lichen planus or molluscum contagiosum.
**Why the Correct Answer is Right**
Lichen nitidus is caused by an autoimmune response, where the body's immune system mistakenly attacks healthy skin cells. The lesions are formed due to the infiltration of lymphocytes into the epidermis, leading to the characteristic shiny, papular appearance. The condition is usually asymptomatic, and the lesions may be confused with other skin conditions due to their small size and uniform appearance.
**Why Each Wrong Option is Incorrect**
* **Option A:** Molluscum contagiosum is a viral skin infection caused by the molluscum contagiosum virus (MCV). It presents with larger, umbilicated lesions, often with a characteristic "dome-shaped" appearance, which is not consistent with the description provided.
* **Option B:** Scabies is a parasitic skin infestation caused by the mite Sarcoptes scabiei. It typically presents with intense itching, particularly at night, and is characterized by small, burrow-like lesions, which is not consistent with the description provided.
* **Option C:** Lichen planus is a chronic inflammatory skin condition characterized by flat-topped, polygonal papules, often with a violaceous color. It typically affects the mucous membranes and skin, and is not consistent with the small, shiny, papular lesions described.
**Clinical Pearl / High-Yield Fact**
Lichen nitidus is often described as having a "grain-of-sand" appearance, due to the small size and uniformity of the lesions. This characteristic appearance should raise suspicion for lichen nitidus, particularly in children.
**✓ Correct Answer: D. Lichen nitidus**