Which method is most used for the diagnosis of bullous pemphigoid?

The most widely used method for diagnosing bullous pemphigoid is direct immunofluorescence microscopy. This technique is crucial because it allows for the visualization of the presence of immunoglobulin and complement deposits at the basement membrane zone of the skin, which is characteristic of this autoimmune blistering disorder. In bullous pemphigoid, the immune system mistakenly attacks proteins in the basement membrane, leading to blisters and erosions.

During direct immunofluorescence, a skin biopsy is taken from a site of active blistering and then treated with fluorescently labeled antibodies. This enables clinicians to identify the specific antibodies that are present in the skin. A positive result, typically showing linear deposition of IgG and complement (C3) at the basement membrane, supports the diagnosis of bullous pemphigoid.

While other diagnostic methods may be used in the context of skin diseases or other systemic diseases, they do not specifically target the unique immunological aspects of bullous pemphigoid. A skin biopsy for epidermolysis, for example, might provide information about skin architecture but would not identify the autoimmune component. Patch testing is used primarily for allergic contact dermatitis and is not relevant for diagnosing bullous pemphigoid, which is