**Question:** Yellow nodules over palm diagnosis

**Core Concept:** Palmoplantar hyperkeratosis is a condition characterized by the thickening and hardening of the skin on the palms and soles, leading to the formation of yellow nodules.

**Why the Correct Answer is Right:** The correct answer is **D** - Palmoplantar pustulosis, also known as Köbner's sign, which is a variant of psoriasis. In this condition, the skin lesions appear as yellowish, sterile pustules on the palms and soles. The formation of these nodules is a characteristic feature of palmoplantar pustulosis.

**Why Each Wrong Option is Incorrect:**

A. **Option A:** Palmoplantar keratoderma is a different entity characterized by hyperkeratosis, not pustulosis. The yellow nodules are the result of hyperkeratosis, not pustules.

B. **Option B:** Palmoplantar psoriasis typically presents with plaques and scales, not pustules. While both conditions may coexist, the correct answer (D) specifically refers to pustulosis.

C. **Option C:** Palmoplantar psoriasis is characterized by plaques, not pustules. Although both conditions can present similarly in some cases, the correct answer (D) refers to pustulosis, a variant of psoriasis.

**Clinical Pearl:** Palmoplantar pustulosis is a variant of psoriasis, with typical clinical features like yellowish sterile pustules on the palms and soles. Recognizing this clinical presentation can help differentiate it from other skin conditions and guide appropriate treatment options.

**Correct Answer:** D. Palmoplantar pustulosis (Köbner's sign) is a variant of psoriasis characterized by yellowish sterile pustules on the palms and soles. This clinical feature is essential to identify as it helps differentiate it from other palmoplantar skin conditions and guides appropriate treatment strategies.