Solitary Fibrous Tumor

A solitary fibrous tumor is an uncommon, usually benign growth that often arises from the pleura, the lining of the lung. It is not caused by asbestos and is not a mesothelioma, although older records sometimes called it "benign fibrous mesothelioma" or "localized mesothelioma." Most are cured by surgery.

Origin

Pleural tumors of this kind were described in the early 1930s and for decades were thought to come from mesothelial cells, hence names like localized fibrous mesothelioma. Later studies showed they come from connective-tissue cells, and they are now classed with soft-tissue tumors. The discovery of a characteristic NAB2-STAT6 gene fusion gave pathologists a reliable test.

Significance in Asbestos Context

A solitary fibrous tumor usually appears as a single, well-defined mass, sometimes large, attached to the pleura by a stalk. It may cause no symptoms and be found by chance, or cause cough or chest discomfort. Pathologists confirm it with immunostains such as STAT6 and CD34; a small share behave aggressively and need closer follow-up. For families and lawyers, the main importance is the name. An old record that says "benign mesothelioma" or "localized fibrous mesothelioma" may describe this tumor, not malignant mesothelioma, and it does not by itself support an asbestos claim. Equally, a true localized malignant mesothelioma is a different and much more serious disease. When older records use these terms, a pathology review of the original slides can settle what the tumor really was.

Example Sentence

The 1978 report called the tumor a "benign fibrous mesothelioma," but a review of the slides with a STAT6 stain showed it was a solitary fibrous tumor.

Related Terms

Mesenchymal Tumor, Benign, CD34, Immunohistochemistry, Pathology Review, Localized Malignant Mesothelioma, Mesothelioma Misclassification, Differential Diagnosis

Notes

• If an old record uses the words "benign" or "localized" mesothelioma, ask for a pathology review of the original slides.
• Ask your surgeon about follow-up scans after removal; a small number of these tumors come back.
• Keep the pathology report and the names of the stains used.