Solitary fibrous tumor

Solitary Fibrous Tumor (SFT) is a rare type of tumor that can occur in any part of the body but is most commonly found in the pleura, which is the thin tissue surrounding the lung. Despite its name, solitary fibrous tumors can sometimes be multiple and can vary greatly in size and behavior. They were first described in the pleura but have since been identified in numerous extrapleural sites, including the meninges, peritoneum, liver, kidney, and orbit. The behavior of solitary fibrous tumors can range from benign to highly malignant.

Etiology and Pathogenesis

The exact cause of solitary fibrous tumors is unknown. They are considered to be of mesenchymal origin, arising from the connective tissue. Genetic studies have shown that the NAB2-STAT6 gene fusion is a frequent finding in SFTs, suggesting a role in the pathogenesis of these tumors.

Clinical Presentation

The symptoms of a solitary fibrous tumor can vary widely depending on its location. Many SFTs are asymptomatic and are discovered incidentally during imaging studies for unrelated reasons. When symptoms do occur, they are often related to the tumor compressing nearby structures. For example, an SFT in the thoracic cavity might cause shortness of breath, chest pain, or cough. An SFT in the central nervous system might present with headaches or neurological deficits.

Diagnosis

The diagnosis of a solitary fibrous tumor typically involves a combination of imaging studies and histopathological examination. Imaging techniques such as CT scans or MRI can help define the size and location of the tumor. However, a definitive diagnosis requires a biopsy of the tumor tissue, followed by microscopic examination and immunohistochemical staining. SFTs are typically positive for the CD34 antigen, BCL-2, and STAT6, the latter being particularly useful in confirming the diagnosis due to its association with the NAB2-STAT6 gene fusion.

Treatment

The treatment of choice for solitary fibrous tumors is surgical resection with the aim of complete removal. The feasibility and extent of surgery depend on the tumor's size, location, and relationship to surrounding structures. In cases where complete resection is not possible or the tumor is malignant, additional treatments such as radiation therapy or chemotherapy may be considered. The role of targeted therapy for SFTs is an area of ongoing research.

Prognosis

The prognosis for individuals with solitary fibrous tumors varies depending on several factors, including the size of the tumor, its location, and whether it is benign or malignant. Benign SFTs that are completely resected generally have an excellent prognosis with a low risk of recurrence. Malignant SFTs, however, can be aggressive and may metastasize to other parts of the body, leading to a poorer prognosis.

Epidemiology

Solitary fibrous tumors are rare, with an incidence that is difficult to determine due to their occurrence throughout the body and the broad range of differential diagnoses. They can occur at any age but are most commonly diagnosed in adults.

See Also

• Tumor
• Pleura
• Mesenchymal Tumor
• CD34
• STAT6