Indirect immunofluorescence on rat bladder epithelium in patients with pemphigus vulgaris with an extended follow-up.

IIF on RBE is a sensitive test for detecting antibodies against plakins. However, it has a relatively high false-positive rate in PV, probably due to the epitope spreading phenomenon. This test should be suggested when there is a clinical or immunohistopathological suspicion of PNP and should be interpreted with caution.