Indirect immunofluorescence on rat bladder transitional epithelium: a test with high specificity for paraneoplastic pemphigus.

BACKGROUND

Paraneoplastic pemphigus is a blistering disease with specific serum immunoprecipitation findings. Although immunoprecipitation studies allow accurate diagnosis, they are time-consuming, expensive, and not readily available. In contrast, indirect immunofluorescence (IIF) testing of serum on transitional rat bladder epithelium is a simple and inexpensive method available to any immunopathology laboratory.

OBJECTIVE

Our purpose was to determine the specificity of positive IIF on rat bladder epithelium for paraneoplastic pemphigus.

METHODS

The IIF findings in four index cases of paraneoplastic pemphigus were compared with the findings in 47 patients with a variety of malignant neoplasms and no associated blistering disease as well as 49 patients with vesiculobullous or lichenoid disease but no neoplasia.

RESULTS

IIF was negative in all patients with neoplasia and no blistering disease and negative in all but one of the patients with vesiculobullous or lichenoid disease without neoplasia (98.9% specificity).

CONCLUSION

IIF on transitional rat bladder epithelium appears to be a highly specific test for paraneoplastic pemphigus. Because of its simplicity and inexpensiveness, we suggest that IIF be performed on transitional epithelium in any suspected case of paraneoplastic pemphigus.