**Question:** Patient with gluten-sensitive enteropathy has a lifelong history of periodic crops of intensely pruritic, grouped, papular or vesicular lesions on the elbows, knees, sacrum, and shoulders. Because the vesicles are intensely pruritic, the patient routinely scratches the top off them, which relieves the pruritus. Which of the following is the most likely diagnosis?

A. Psoriasis
B. Atopic dermatitis
C. Lupus erythematosus
D. Gluten-sensitive enteropathy

**Core Concept:**

Gluten-sensitive enteropathy, also known as celiac disease, is a chronic autoimmune disorder characterized by an intolerance to gluten, a protein found in wheat, barley, and rye. In this condition, ingestion of gluten leads to an immune response in the small intestine, causing inflammation, damage, and malabsorption of nutrients. The classical presentation includes diarrhoea, malabsorption, and weight loss.

**Why the Correct Answer is D:**

The correct answer is D: Gluten-sensitive enteropathy, also known as celiac disease. The clinical presentation described in the question, with periodic crops of pruritic lesions on exposed areas, is a common manifestation of celiac disease. The intense pruritus, vesicles, and relief upon scratching are consistent with the skin manifestations of celiac disease.

**Why Other Options are Incorrect:**

A. Psoriasis: Psoriasis is a chronic, inflammatory skin disorder characterized by scaly plaques with distinct clinical features such as sharply demarcated erythema, silvery scales, and a predilection for elbows, knees, and scalp. While both psoriasis and celiac disease can present with pruritus, the distribution of lesions, clinical features, and relief upon scratching are not consistent with psoriasis.

B. Atopic dermatitis (Atopic Dermatitis): Atopic dermatitis refers to a group of skin disorders that include eczema, asthma, and hay fever. The clinical presentation described in the question does not match the typical clinical features of atopic dermatitis, such as dry, red, and scaly skin with a predilection for flexural areas and the face. Furthermore, relief of symptoms upon scratching is not a typical feature of atopic dermatitis.

C. Systemic lupus erythematosus (Lupus): Systemic lupus erythematosus is a chronic autoimmune disease affecting multiple organ systems, including the skin. Clinical features like symmetrical, photosensitive rash, mucosal involvement, and joint symptoms are not present in the given scenario. Additionally, relief from symptoms upon scratching is not a typical feature of systemic lupus erythematosus.

**Clinical Pearls:**

1. The relief of symptoms upon scratching is a key feature that differentiates celiac disease from other skin conditions.
2. The distribution of lesions (pruritic vesicles/pustules on the elbows, knees, and buttocks) and relief on scratching are characteristic of