**Question:** A 5–year old child presents with perivascular IgA deposition and neutrophil collection. There is erythematous rash on the lower limb and non-blanching purpura. Probable diagnosis is –

A. Henoch-Schönlein Purpura
B. Henoch-Schönlein Purpura
C. Urticaria
D. Erythema Elevatum Diutinum

**Correct Answer:** D. Erythema Elevatum Diutinum

**Core Concept:**

Perivascular IgA deposition and neutrophil collection are key features in various dermatological conditions. IgA is an immunoglobulin found primarily in the mucous membranes and the small intestine. Perivascular deposition of IgA can be seen in a few conditions, but in the context of a 5-year-old child presenting with these findings, the diagnosis should be narrowed down based on the rash location and clinical features.

**Why the Correct Answer is Right:**

Erythema Elevatum Diutinum (EED) is a rare, idiopathic dermatosis characterized by indurated, erythematous plaques with a targetoid appearance, often involving the lower limbs. It is characterized by perivascular IgA deposition, neutrophil infiltration, and typically presents in children and young adults.

On the other hand, Henoch-Schönlein Purpura (HSP) is a common pediatric vasculitis presenting with palpable purpura, abdominal pain, arthralgia, and renal involvement. Erythema Elevatum Diutinum does not involve renal involvement or arthralgia and is more commonly seen in children and young adults, while HSP is more common in older children and adolescents.

**Why Each Wrong Option is Incorrect:**

A. Henoch-Schönlein Purpura: Although Henoch-Schönlein Purpura can present with a similar rash, it usually involves renal involvement, which is not present in this case.

B. Henoch-Schönlein Purpura: In addition to renal involvement, HSP is more common in older children and adolescents, whereas Erythema Elevatum Diutinum is seen in younger age groups.

C. Urticaria: Urticarial rashes are characterized by wheals, not erythematous plaques. Urticarial lesions are typically caused by histamine release from activated mast cells, whereas Erythema Elevatum Diutinum involves perivascular IgA deposition and neutrophil infiltration.

D. Erythema Elevatum Diutinum: As mentioned earlier, HSP is more common in older children and adolescents, while Erythema Elevatum Diutinum is seen in younger age groups and lacks renal involvement.

**Clinical Pearls:**
Erythema Elevatum Diutinum is a rare dermatosis affecting children and young adults. It is characterized by non-blanching, indurated, erythematous plaques. The rash is typically located on the lower