reactive pleuritis

Surface injury and ulceration lead to the proliferation of epithelioid mesothelial cells.

Reactive mesothelial cells exhibit morphological abnormalities that include nuclear atypicality, increased mitotic index, architectural complexity, apoptosis, and coagulative necrosis.

When atypical epithelioid mesothelial hyperplasia (AEMH) proliferation is present, it can be difficult to distinguish from malignant mesothelioma (MM).

The pleural response to injury includes the proliferation of submesothelial spindle cells and the deposition of a myxomatous collagenous matrix.

Neoangiogeneis from the systemic bronchial circulation is an integral feature of pleural wound repair and is characterized by the proliferation of thin-walled capillary-like vessels with endothelial cell activation and thickened basement membranes. The architecture of the vascular response is a helpful feature in distinguishing inflammation from neoplasia.

Reactive neovasculature tends to penetrate the pleura at right angles to the inflamed surface, whereas tumor vasculature is aligned haphazardly manner.

However, this feature may be obscured by the fact that malignant disease and reactive pleuritis often coexist side by side in the same biopsy.

See also

 reactive mesothelial response