Solitary fibrous tumors are rare growths of cells that can appear in nearly any part of the body. These tumors originate from connective tissues, which support other body tissues. While most solitary fibrous tumors are noncancerous, some can be malignant and spread to other areas.
Understanding Solitary Fibrous Tumors
Solitary fibrous tumors (SFTs) are a type of mesenchymal tumor, meaning they arise from mesenchymal tissue. These tumors are rare, accounting for less than 1% of all soft tissue tumors. They are composed of fibroblasts and related cell types.
While SFTs can develop anywhere, they most frequently occur in the pleura, the protective tissue lining the chest cavity and covering the lungs. They have also been identified in various other locations such as the head and neck, breast, kidney, prostate, and spinal cord. Although most SFTs are benign, a small percentage, approximately 10-15%, can exhibit malignant behavior, including recurrence after surgery or metastasis.
Identifying and Diagnosing Solitary Fibrous Tumors
Solitary fibrous tumors often grow slowly and may not cause symptoms until they become large enough to press on nearby organs or tissues. Many individuals with these tumors do not experience symptoms, with tumors often discovered incidentally during imaging tests. When symptoms do occur, they depend on the tumor’s location. For tumors in the chest cavity, symptoms may include chronic cough, shortness of breath, or noncardiac chest pain. Enlarged fingertips and abnormal nail growth, known as clubbed fingers, can also occur.
The diagnostic process typically begins with imaging techniques such as X-rays, CT scans, and MRI scans, which can help locate the tumor and assess its size. A definitive diagnosis of a solitary fibrous tumor is made through a tissue biopsy, where a small piece of the tumor tissue is removed and examined under a microscope by a pathologist. This microscopic examination reveals specific histological features, and immunohistochemical staining often confirms the diagnosis by identifying the NAB2-STAT6 fusion gene, a genetic alteration commonly associated with SFTs.
Treatment Options
The primary treatment for solitary fibrous tumors is complete surgical removal of the tumor. Surgeons aim to remove the entire tumor along with a small margin of surrounding healthy tissue to reduce the risk of recurrence.
In some situations where the tumor cannot be entirely removed, or if it is malignant or has spread, other treatments may be considered. Radiation therapy might be used, sometimes before surgery to shrink the tumor. Chemotherapy is another option, particularly if the tumor has spread to other parts of the body. Targeted medications that disrupt the tumor’s blood supply, such as those that target vascular endothelial growth factor (VEGF) pathways, have also been used for advanced cases to slow tumor progression.
Life After Diagnosis: Prognosis and Monitoring
The prognosis for individuals with solitary fibrous tumors generally depends on whether the tumor can be completely removed through surgery. While most SFTs are benign, factors such as tumor size, location, increased cellularity, mitotic activity (rate of cell division), and the presence of necrosis (tissue death) can influence the long-term outlook and the likelihood of the tumor returning. Tumors are often categorized into low, intermediate, or high-risk groups based on these characteristics to predict their behavior.
Due to the potential for late recurrence, even after successful treatment of benign tumors, long-term follow-up and regular monitoring are important. This ongoing surveillance typically involves periodic imaging scans to detect any signs of recurrence early.