**Question:** 10 year old child has violaceous papule and pterygium of nails. The diagnosis is –

A. Discoid lupus erythematosus
B. Pemphigus vulgaris
C. Sweet syndrome
D. Kawasaki disease

**Correct Answer:** **D. Kawasaki disease**

**Core Concept:** Kawasaki disease is a systemic vasculitis affecting children, characterized by fever, mucocutaneous changes, and inflammation of small and medium-sized vessels.

**Why the Correct Answer is Right:** Kawasaki disease presents with a characteristic set of symptoms and signs that help differentiate it from other conditions listed here. Violaceous papules and pterygium of nails are indicative of mucocutaneous changes, which are a hallmark feature of Kawasaki disease. These lesions are likely due to the vasculitis affecting the blood vessels in the skin and nail beds.

**Why Each Wrong Option is Incorrect:**

A. Discoid lupus erythematosus (DLE) typically presents in adults and exhibits chronic and relapsing course. The lesions are typically annular and scaly rather than papular.
B. Pemphigus vulgaris is an autoimmune blistering disorder affecting skin, mucous membranes, and internal organs. Its clinical features differ from those of Kawasaki disease.
C. Sweet syndrome is a neutrophilic dermatosis characterized by acute febrile neutrophilic dermatitis. The lesions are often tender and preceded by an acute infection or malignancy.

**Clinical Pearl:** Violaceous papules and pterygium of nails in a pediatric patient should raise suspicion for Kawasaki disease, especially when associated with fever and mucocutaneous changes. A comprehensive clinical examination, including the patient's history, should be performed to confirm the diagnosis.

**Core Concept:** Kawasaki disease is a vasculitis affecting children and is associated with fever, mucocutaneous changes, and cervical lymphadenopathy (swollen lymph nodes). It is named after Dr. Tomisaku Kawasaki, who first described this condition in Japan in 1967.

**Why Each Wrong Option is Incorrect:**

A. Discoid lupus erythematosus (DLE) is an autoimmune disease affecting skin and joints. It is characterized by chronic and relapsing lesions, and is not associated with fever and mucocutaneous changes.

B. Pemphigus vulgaris is a chronic autoimmune disorder characterized by blisters in the skin, oral mucous membranes, and internal organs. It typically affects adults and is not associated with fever and mucocutaneous changes.

C. Sweet syndrome is an acute febrile neutrophilic dermatosis characterized by tender papules and plaques. It is often associated with preceding infections or malignancies, which is not the case in Kawasaki disease.

**Clinical Pearl:** The presence of fever and mucocutaneous changes should prompt the clinician to consider Kawasaki disease in a pediatric