Objective: Presentation of a case of biphasic pleural mesothelioma with
reference to difficulties concerning differential diagnosis from reactive
Patients and methods: We present a case of a 76-year-old woman,
which was found with total thickening of her left pleura and nodular
infiltrations with hemorrhagic fluid in her CT-scan of thorax.
Histological examination of bioptic material revealed high cellular tissue presence with parietal pleura texture. There were also several cells with
epithelioid appearance, large clear nuclei with small nucleoli inside a
fibrous layer. Immunohistochemical stains were positive for Vimentin,
Ck7, Ck5/6, Calretinin, and WT-1. EMA had moderate membrane
staining, whereas proliferation index Ki-67 was highly expressed.
Results: The above morphological and immunohistochemical results
do not clarify the differential diagnosis between biphasic pleural
mesothelioma from reactive mesothelial proliferations.
Conclusions: Reactive mesothelial proliferations may mimic malignant
mesothelioma. High cellularity, the presence of numerous mitotic
figures, cytologic atypia and the presence of necrosis are features of both
reactive mesothelial proliferations and malignant mesothelioma. On the
other hand, demonstration of stromal infiltration and positive staining
in markers such as EMA and p53 strongly indicate the presence of
malignant mesothelioma. In any case, it is mandatory to take in advance
clinical, imaging and operative features, in order to establish safely a