Figure 4.

Expression of SDHA, SDHB and COX-IV in SDHA-mutated paraganglioma compared with other inherited paraganglioma/pheochromocytoma. SDHA-positive immunostaining is observed in the chromaffin cells of SDHB- and RET-related tumors. In the patient's tumor, it is detected solely in blood vessels and not in tumor cells. SDHB protein expression is lost in both SDHA- and SDHB-mutated tumors, whereas it is still present in RET-related pheochromocytomas. Subunit COX-IV of mitochondrial cytochrome c oxidase is expressed at comparable levels in all tumors. Calibration bar: 100 µm.