Efficacy of Immunohistochemistry for SDHB in the Screening of Hereditary Pheochromocytoma-Paraganglioma.

The most common genetic backgrounds of hereditary paraganglioma and pheochromocytoma (PPGL) are germline mutations. Given the fact that the immunohistochemistry (IHC) result for SDHB is always negative regardless of the type of mutation, we aimed to evaluate the efficacy of using SDHB IHC for screening mutations in PPGL cases. In total, 52 patients who underwent surgery for PPGL treatment between 2006 and 2020 and underwent genetic analysis at diagnosis were included. Tissue microarrays (TMAs) were constructed with PPGL tissues and IHC for SDHB was performed on TMA sections. All 10 patients with SDHB-negative IHC contained or mutations. The genetic test results of patients with SDHB-weakly positive IHC varied (one , two , one , and three unknown gene mutations). There were no mutations in the SDHB-positive IHC group. Six patients with weakly positive SDHB IHC with primarily unknown genetic status were re-called and underwent next-generation sequencing. None of them had mutations. In conclusion, SDHB-negative IHC is a cost-effective and reliable method to predict mutations. However, in the case of weakly positive SDHB staining, an additional gene study should be considered.