Difrencess benign mesothelial hyperplasia from malignant pleural mesothelioma

As emphasised earlier in this chapter, the demonstration of fat or stromal tissue invasion
by histology or imaging is an essential criterion for definitive diagnosis of malignant
pleural mesothelioma.
Although reactive mesothelial proliferations are non-invasive, entrapment of benign
mesothelial cells within the fibrous tissue of organising inflammation can simulate
neoplastic invasion . This can make histological discrimination between
entrapment and invasion difficult. It is recommended that when invasion cannot be
identified in biopsy tissue, the lesion should be designated as an atypical mesothelial
proliferation
Clinical decision-making for a diagnosis of malignant mesothelioma may be made when
a limited biopsy has shown an atypical mesothelial proliferation without invasion. This
requires correlation with imaging studies, a more adequate biopsy or, in many instances,
serial imaging studies to ascertain whether the lesion is progressive