Manganese superoxide dismutase as a diagnostic marker for malignant pleural mesothelioma

Although several immunohistochemical markers are available, differential di agnosis between mesothelioma and metastatic adenocarcinoma of the pleura is difficult. We have found that the immunoreactivity of manganese superoxide dismutase (MnSOD), an important antioxidant enzyme, is high in mesotheliom a compared to healthy pleural mesothelium. The aim of the present study was to investigate whether MnSOD can be used in the differential diagnosis of malignant mesothelioma and metastatic adenocarcinoma of the pleura. MnSOD e xpression was assessed by using immunohistochemistry in biopsies of maligna nt mesothelioma (n = 35) and metastatic adenocarcinoma of the pleura (n = 2 1). MnSOD immunoreactivity was assessed semiquantitatively with and without microwave pretreatment Fifteen of the 35 malignant mesotheliomas showed mo derate or strong MnSOD expression without and 23 with microwave pretreatmen t, the corresponding figures for metastatic adenocarcinoma of the pleura be ing 1 and 2 out of 21 (P = 0.002 and P < 0.001, respectively by Fisher's ex act test), Only mesothelioma biopsies showed strong MnSOD reactivity, and i t was never negative in mesothelioma, whereas one-third of the adenocarcino mas showed no MnSOD reactivity. in conclusion, MnSOD immunoreactivity can. combined with other markers, aid the differential diagnosis between maligna nt mesothelioma and metastatic adenocarcinoma of the pleura, (C) 2000 Cance r Research Campaign.