Solitary Fibrous Tumor

What is Solitary Fibrous Tumor?

The mass called solitary fibrous tumor is a rare malignancy that has a mesenchymal origin. This type of neoplasm makes up about 2% of all soft tissue tumors. Although most of it cases are benign, 1 in every 5 cases are found to be malignant [1, 2].

A typical solitary fibrous tumor is made up of fibroblasts and other related cell types. The mesenchyme, from which this tumor originates, is one of the 3 primary germ layers of an embryo. This structure gives rise to the dermis of the skin, connective tissues, muscles and bones. Most of solitary fibrous tumors develop in the intrathoracic area but about 33% of the cases show an extrathoracic growth. The prognosis of this tumor is dependent on the possibility of surgically removing the tumor [2, 3, 4]. 

solitary fibrous tumor

solitary fibrous tumor

Figure 1 – shows an image of a solitary fibrous tumor.


Solitary fibrous tumors may develop in individuals aged 20-70 but a majority of cases is found in those who are between 40-50 years of age. It is also less commonly found in children and infants. There is a similar incidence between male and female [1, 4].

Causes and Risk Factors

The exact cause of this neoplasm is still unknown. There are genetic mutations that may have been detected but further research is required to describe these anomalies. No risk factors have been associated with this condition as of this writing [1, 4].

Signs and Symptoms

The presenting signs and symptoms depend on the size and location of the tumor. Tumors that are less than 10cm may not present with any symptom unless they compress on surrounding organs in which the patient may feel pain in that area. Limitation of joint movement may occur if the mass developed near a joint. Solitary fibrous tumor of the pleura may cause shortness of breath and cough [3, 4].

A solitary fibrous tumor may secrete Insulin-like Growth Factor-2 (IGF-2) and cause hypoglycemia. The patient may present sweating, confusion, alteration in mental status, cold hands and dizziness [3, 4].


Establishing a diagnosis involves an evaluation of the patient’s medical history and physical examination. Imaging studies such as X-rays, Computed Tomography (CT) scan and Magnetic Resonance Imaging (MRI) will be able to provide a visualization of the tumor growth. These scans will also aid in detecting the possibility of metastasis in other areas of the body [1, 4].

Tissue biopsies may be obtained by a pathologist for an examination. The histologic arrangement of solitary fibrous tumor is similar to other malignancies. Its immunoreactivity to CD34, a hematopoietic stem cell marker, is useful in the differential diagnosis [1, 4].


Although there is no protocol for treatment for solitary fibrous tumor, a surgical excision with wide or clear margins is usually the preferred treatment modality. This can provide a cure to the patient especially if the tumor is benign. A long-term follow-up may be required of patients after the surgical procedure to monitor their status. Even benign tumors may develop metastasis even after several years [4].

Radiotherapy and chemotherapy may be used as the primary therapy option if it is not possible to surgically excise the mass or if the tumor has recurred. Metastasis of the tumor may be treated with chemotherapeutic drugs [4].


  1. Ng, V. (2015, March 4). Solitary Fibrous Tumor. Retrieved from Medscape:
  2. Weerakkody, Y., & Niknejad, M. T. (2016). Solitary fibrous tumour. Retrieved from Radiopaedia:
  3. DoveMed. (2015, October 15). Solitary Fibrous Tumor. Retrieved from DoveMed:
  4. Ali, S., Hoon, V., Hoda, S., & Heelan, R. (1997). Solitary fibrous tumor. Cancer Cytopathology, 116-121.

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