What are the key clinical features to consider when diagnosing bullous pemphigoid in an elderly patient?

Key clinical features to consider when diagnosing bullous pemphigoid in an elderly patient include:

• Age and presentation: Typically affects elderly patients, often over 60 years old, presenting with tense, large, fluid-filled blisters (bullae) on normal or erythematous skin.
• Pruritus: Intense itching is a prominent early symptom, often preceding blister formation by weeks to months.
• Distribution: Lesions commonly involve the flexor surfaces of limbs, lower abdomen, and groin, but can be widespread.
• Non-mucosal involvement: Unlike some other blistering diseases, mucous membrane involvement is less common but can occur.
• Prodromal phase: May present initially with urticarial or eczematous plaques before bullae develop.
• Blister characteristics: Bullae are typically tense and do not rupture easily, reducing risk of secondary infection compared to other blistering disorders.
• Associated symptoms: Patients may have malaise or systemic symptoms, but these are usually mild or absent.
• Diagnostic clues: Negative Nikolsky sign (skin does not shear off with lateral pressure) helps differentiate from pemphigus vulgaris.

These clinical features, combined with patient age and presentation, guide the diagnosis of bullous pemphigoid, which should then be confirmed by immunofluorescence and serological testing as per clinical guidelines NICE CKS Di Zenzo et al. 2007Schmidt et al. 2011Ruggiero et al. 2022.