**Question:** Band shaped keratopathy seen in:

A. Corneal grafts
B. Diabetes mellitus
C. Pemphigus vulgaris
D. Pemphigus foliaceus

**Core Concept:** Band shaped keratopathy is a clinical entity characterized by the appearance of corneal opacities arranged in a band-like pattern. These opacities are typically seen in conditions affecting the cornea or the adjacent structures.

**Why the Correct Answer is Right:** Band shaped keratopathy is associated with Pemphigus vulgaris, which is an autoimmune disease that affects the skin and mucous membranes. In this condition, the immune system attacks the desmoglein proteins, causing blister formation and eventually leading to band shaped keratopathy.

**Why Each Wrong Option is Incorrect:**

A. Corneal grafts: Band shaped keratopathy is not a complication of corneal grafts. Instead, graft rejection or complications like graft-versus-host disease (GVHD) are more common after corneal grafts.

B. Diabetes mellitus: Although diabetes may cause various ocular complications, band shaped keratopathy is not a common manifestation of diabetic keratopathy. The main ocular complications seen in diabetes include diabetic retinopathy, cataracts, and glaucoma.

C. Pemphigus foliaceus: Pemphigus foliaceus is another autoimmune disease affecting the skin, but it is distinct from pemphigus vulgaris. The two diseases have different clinical presentations and are caused by distinct autoantibodies targeting different desmoglein proteins.

D. Pemphigus foliaceus: Similar to option C, pemphigus foliaceus is a different autoimmune disease affecting the skin and not the cornea. It is caused by autoantibodies targeting desmoglein 1, which is different from desmoglein 3 targeted in pemphigus vulgaris.

**Clinical Pearl:** Pemphigus is a group of autoimmune diseases characterized by blister formation in the mucocutaneous junctions due to autoantibodies targeting desmoglein proteins. Pemphigus vulgaris is associated with desmoglein 3 antibodies, leading to the band-shaped keratopathy.

**Core Concept:** Band shaped keratopathy is a clinical manifestation of autoimmune diseases targeting desmoglein proteins. The correct answer (Pemphigus vulgaris) involves an autoimmune response against desmoglein 3, leading to blister formation in the mucocutaneous junctions.

**Why Each Wrong Option is Incorrect:** The autoimmune response in these diseases results in blister formation, not band-shaped keratopathy. Options A, B, C, and D involve autoimmune diseases targeting different desmoglein proteins (desmoglein 1, 2, or 3) and cause different clinical presentations, not band-shaped keratopathy.