Immunohistochemistry and genetic analysis tend to add little to the impression obtained by routine histology. PPB commonly shows staining for desmin and myogenin in areas of obvious rhabdomyosarcomatous differentiation as well as in a subset of the primitive subepithelial cells. S100 protein is typically limited to the cartilaginous nodules. Cytokeratin highlights the benign lining mesothelium/epithelium but is negative in the tumor cells.
Pathologists are asked to consider sending tissue to the PPB/DICER1 Registry Tissue Bank. For details, see Tissue Bank.