Reverse Koebner Phenomenon in Bullous Pemphigoid - A Case Report

Area of Science:

• Dermatology
• Immunodermatology

Background:

• The Koebner phenomenon describes lesion development at injury sites in certain skin conditions.
• The reverse Koebner phenomenon is characterized by the absence or regression of dermatosis lesions at sites of trauma.

Observation:

• A 35-year-old male patient with bullous pemphigoid presented with lesions sparing his waist area.
• This sparing was hypothesized to be due to the locus majoris resistentiae phenomenon.

Findings:

• Histopathology of affected skin revealed subepidermal splitting and a mixed inflammatory infiltrate (eosinophils, neutrophils, lymphocytes).
• Histopathology of the spared skin showed no abnormalities.
• Direct immunofluorescence from perilesional skin demonstrated linear deposits of immunoglobulin G and C3 at the dermoepidermal junction, absent in the spared skin.

Implications:

• This case highlights an unusual presentation of bullous pemphigoid and the reverse Koebner phenomenon.
• It underscores the importance of considering localized resistance phenomena in dermatological presentations.
• The findings contribute to understanding the complex interplay between skin injury and autoimmune blistering diseases.