What is the diagnosis for a 25-year-old woman presenting with an itchy rash and vesicles on the skin, with direct immunofluorescence showing IgA deposits?

In this scenario, the diagnosis of dermatitis herpetiformis is supported by the presence of an itchy rash and vesicles on the skin, along with the finding of IgA deposits noted through direct immunofluorescence. Dermatitis herpetiformis is a chronic skin condition associated with gluten sensitivity and is characterized by intensely itchy lesions that often present as small vesicles.

The formation of vesicles occurs because of the deposition of immune complexes in the dermal papillae, which causes damage and inflammation at the site, leading to the characteristic blistering and rash. The immunofluorescence staining that shows IgA deposits at the tips of dermal papillae is a hallmark finding that confirms this diagnosis, distinguishing it from other blistering disorders.

In contrast to other conditions listed, such as bullous pemphigoid and pemphigus, which typically show different immunofluorescence patterns (such as IgG and complement deposits in the case of bullous pemphigoid and intercellular IgG in pemphigus), dermatitis herpetiformis specifically demonstrates these IgA deposits, linking it to dietary triggers and coeliac disease. Additionally, epidermolysis bullosa acquisita is often associated with different types of auto