Solitary Fibrous Tumor of the Pleura

27 Feb

Solitary Fibrous Tumor of the PleuraA Report of Five Cases Diagnosed by Transthoracic Cutting Needle Biopsy
Solitary fibrous tumor of the pleura is a rare entity, and it is also known as benign localized mesothelioma, submesothelioma, or subserosal fibroma. This tumor arises usually from the visceral pleura (in 80% of the cases), but it can also derive from the parietal pleura and other serosal membranes, such as the peritoneum and the pericardium. It can even occur in nonserosal sites, such as the pulmonary parenchyma, the mediastinum, the nose, and the paranasal sinuses. Its histogenesis is still a matter of debate, but this tumor usually is considered to be derived from a mesenchymal cell. In five patients, the diagnosis was made from a biopsy by transthoracic cutting needle (Tru-Cut; Travenol; Deerfield, IL). This technique is routinely used at Universite Catholique de Louvain to obtain material for histologic and immunohistochemical analysis of parietal, pleural, or peripheral lung lesions with pleural contact.

Materials and Methods
Five patients underwent a fluoroscopically guided transthoracic needle biopsy with the use of a 22G Rotex II screw needle instrument (Ursus Konsult AB; Stockholm, Sweden), which was immediately followed by a 14G cutting needle biopsy in order to obtain material for cytologic and histologic studies, respectively. Cytologic smears were stained with the classic Papanicolaou method, whereas the Allen-Bouin-fixed and paraffin-embedded biopsy specimens were stained with hematoxylin-eosin or prepared for immunohistochemical analysis. The following antibodies were applied: mouse monoclonal anti-low molecular weight cytokeratin (clone CAM 5.2; Becton Dickinson; Erembodegem, Belgium), a marker of epithelial cells; mouse monoclonal anti-vimentin (Dakopatts; Glostrup, Denmark), a mesenchymal marker; mouse monoclonal anti-actin (Enzo Diagnostics; New York); and rabbit polyclonal anti-desmin (Dakopatts; Glostrup, Denmark), both specific for smooth muscle and mouse monoclonal anti-CD34 (clone QBEND10; Novocastra Laboratories; Newcastle upon Tyne, England), whose specificity and utility will be detailed in the discussion.
When surgically obtained specimens were available, the tumors were fixed in formaldehyde and further treated in the same way as the biopsy specimens.