Narrowband UVB-induced lichen planus pemphigoide.

Area of Science:

• Dermatology
• Autoimmunology
• Phototherapy

Background:

• Lichen planus pemphigoides (LPP) is a rare autoimmune blistering disease.
• It presents with subepidermal blisters on normal or lichen planus-affected skin.
• Distinguishing LPP from other blistering disorders is crucial for accurate diagnosis and management.

Observation:

• A 54-year-old Chinese woman initially diagnosed with guttate psoriasis received narrowband ultraviolet B (NBUVB) therapy.
• Following NBUVB, she developed a generalized eruption of violaceous papules, bullae on lower limbs, and Wickham's striae.
• Histopathology confirmed interface dermatitis and subepidermal bullae; direct immunofluorescence showed linear IgG and C3 deposition.

Findings:

• Clinicopathological correlation led to a diagnosis of LPP.
• This is the first reported case where NBUVB therapy alone unmasked LPP.
• The study details the pathological mechanism of NBUVB in inducing LPP and differentiates LPP from similar conditions.

Implications:

• NBUVB therapy can potentially trigger or unmask LPP in susceptible individuals.
• Understanding the role of phototherapy in LPP pathogenesis is important for dermatologists.
• This case underscores the need for careful monitoring during phototherapy and highlights key diagnostic features of LPP.