A 20-year-old female presented to the dermatology OPD with skin lesions which were itchy, violaceous, shiny flat topped, polygonal papules of various sizes on flexor surface of wrist. These when viewed under a magnifying lens, surface of the lens showed ceain streaks which were enhanced by putting a drop of mineral oil on the lesions. Koebner’s phenomena was present. On examination, some lesions were observed in the oral mucosa along with erosive lesions on tongue. Nails showed thinning and distal splitting of nail plates, longitudinal ridging and pterygium.

**Core Concept**
The patient's presentation is characteristic of a chronic autoimmune skin disorder that affects not only the skin but also mucous membranes and nails. This condition is marked by specific histopathological features and clinical manifestations.

**Why the Correct Answer is Right**
The clinical features described are consistent with Psoriasis, a chronic inflammatory skin disease that affects approximately 2% of the global population. The presence of violaceous, shiny, flat-topped papules on the flexor surfaces, particularly on the elbows and knees, is a hallmark of the disease. The characteristic Koebner phenomenon, where skin lesions appear at sites of trauma, further supports this diagnosis. The involvement of mucous membranes, nails, and the presence of pterygium are also consistent with Psoriasis. The enhancement of the dermatoglyphics by mineral oil is a classic sign of Psoriasis.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect as it does not match the clinical presentation of Psoriasis. The lesions described in this option are more consistent with Lichen Planus, which is characterized by purplish, itchy, flat bumps on the skin, but lacks the characteristic dermatoglyphics enhancement by mineral oil.
* **Option B:** This option is incorrect as it does not match the clinical presentation of Psoriasis. The lesions described in this option are more consistent with Eczema, which is characterized by itchy, inflamed skin, but lacks the characteristic dermatoglyphics enhancement by mineral oil.
* **Option C:** This option is incorrect as it does not match the clinical presentation of Psoriasis. The lesions described in this option are more consistent with Dermatomyositis, which is characterized by skin rash, muscle weakness, and inflammation, but lacks the characteristic dermatoglyphics enhancement by mineral oil.
* **Option D:** This option is incorrect as it does not match the clinical presentation of Psoriasis. The lesions described in this option are more consistent with Pityriasis Rubra Pilaris, which is characterized by orange-red, scaly patches on the skin, but lacks the characteristic dermatoglyphics enhancement by mineral oil.

**Clinical Pearl / High-Yield Fact**
The presence of pterygium in Psoriasis is a high-yield fact that can help differentiate it from other skin conditions. Pterygium is a characteristic feature of Psoriasis that involves the formation of a scar tissue band that can cause the nail to split or become detached from the nail bed.

**Correct Answer:** C.

✓ Correct Answer: A. Lichen planus