A 30 years old male presented with silvery scales on elbow and knee, which bleed on removal. The probable diagnosis is:
**Core Concept**
The patient's presentation of silvery scales on elbow and knee that bleed on removal is characteristic of a specific skin condition involving abnormal keratinization and hyperproliferation of skin cells.
**Why the Correct Answer is Right**
The patient's symptoms are consistent with psoriasis, a chronic autoimmune disorder that affects the skin. Psoriasis is characterized by the abnormal proliferation of skin cells, leading to the formation of thick, scaly plaques. The silvery scales on the elbow and knee are a hallmark of psoriasis, and the bleeding on removal is due to the thinning of the epidermis and the underlying dermis. The exact pathophysiology involves the activation of T lymphocytes and the release of inflammatory cytokines, which contribute to the hyperproliferation of skin cells.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because it does not match the patient's presentation of silvery scales and bleeding on removal.
* **Option B:** This option is incorrect because it refers to a different skin condition, such as eczema, which typically presents with itching, redness, and edema, but not silvery scales.
* **Option C:** This option is incorrect because it refers to a different skin condition, such as seborrheic dermatitis, which typically presents with yellowish, oily scales, but not silvery scales.
**Clinical Pearl / High-Yield Fact**
Psoriasis is often associated with other systemic conditions, such as psoriatic arthritis, and can be triggered by various factors, including stress, infections, and certain medications.
**Correct Answer: D. Psoriasis**