A patient has extensive painful erosions of the oral mucosa but intact skin. Biopsy shows suprabasal acantholysis with a tombstone row of basal keratinocytes. The selective involvement of mucosa alone is best explained by:
- A Antibodies against desmoglein 1 only
- B Antibodies against BP180 causing mucosal lysis
- C Antibodies against desmoglein 3 only, since skin expresses enough desmoglein 1 to maintain adhesion ✓
- D Complement-mediated destruction of anchoring fibrils
Correct answer: C. Antibodies against desmoglein 3 only, since skin expresses enough desmoglein 1 to maintain adhesion
Explanation
Desmoglein 3 predominates in mucous membranes while both desmoglein 1 and 3 are expressed in skin. Antibodies to desmoglein 3 alone disrupt mucosal adhesion, but skin remains intact because desmoglein 1 compensates there. This is the desmoglein compensation theory. Mucocutaneous pemphigus vulgaris occurs when desmoglein 1 antibodies coexist, which is why option A describes the opposite phenotype.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.