Which test confirms the diagnosis of pemphigus vulgaris?

The diagnosis of pemphigus vulgaris is confirmed through histological immunofluorescence, which is a critical diagnostic tool in evaluating this condition. Pemphigus vulgaris is an autoimmune disorder characterized by the presence of autoantibodies against desmogleins, which are critical components of the cell adhesion in the epidermis.

In this procedure, skin biopsy samples are analyzed using immunofluorescence techniques to detect the binding of antibodies to the intercellular spaces, thus demonstrating the loss of cell adhesion seen in the disease. The presence of these autoantibodies in the skin allows for a definitive diagnosis, distinguishing it from other blistering disorders.

Other methods, while useful in different contexts, do not provide a definitive diagnosis. For instance, Tzanck smear can reveal acantholytic cells, but it lacks specificity for pemphigus vulgaris as it can also be seen in other conditions. A test dose of corticosteroid could potentially exhibit improvement in symptoms but does not confirm the diagnosis. Serological tests for auto antibodies can support the diagnosis but are not definitive alone without the histological evidence. Thus, histological immunofluorescence remains the gold standard for confirming pemphigus vulgaris.