Solitary fibrous tumor

Malignant Solitary Fibrous Tumor of the Right Cerebellum

Solitary fibrous tumor (SFT) is a rare mesenchymal tumor that occurs mostly in the pleura. It was first reported and named by Klemperer and Rabin in 1931. The 2016 WHO classification of central nervous system tumors combines intracranial solitary fibrous tumor with hemangiopericytoma (HPC) into the same category, using the combined term SFT/HPC.

Case Presentation

This patient was a 63-year-old Chinese man who was admitted to our hospital for 1 week of walking instability. Eight years ago, this patient suffered from headache and dizziness symptoms and was diagnosed with atypical solitary fibrous tumor. The patient was treated twice with gamma knife radiosurgery after the surgery, and no adjuvant radiotherapy was used. In addition to walking instability, there were no symptoms such as nausea and vomiting. Moreover, there was no other medical history, including hypertension and diabetes. A brain magnetic resonance imaging (MRI) scan revealed a 5.1 × 4.1 × 2.6 cm homogeneous mass located in the right cerebellum (Fig. 1).

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MRI showing the right cerebellum space-occupying lesion on T1-weight image.

After discussion in the department, the patient underwent a craniotomy and resection of tumor. During the surgery, the tumor’s color was yellow-white, soft in texture, rich in blood supply, and there are obvious boundaries between tumor and surrounding tissues. Postoperative pathological report suggested a malignant solitary fibrous tumor, the tumor cells were positive for Vimentin, CD99 (Fig. 2), bcl-2 (Fig. 3) and CD34 (Fig. 4), EMA, S100 and GFAP were negative. Ki-67 immunostaining showed a 30% proliferative index (Fig. 5). Histological examination showed that the tumor was composed of spindle cells (Fig. 6). The patient was discharged with no symptoms such as limb paralysis. Three months after the operation, MRI showed that the tumor was completely removed and no recurrence was found (Fig. 7).

Tumor cells showing diffuse immunohistochemical positivity for CD-99.

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Tumor cells showing diffuse immunohistochemical positivity for Bcl-2.

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Tumor cells showing diffuse immunohistochemical positivity for CD-34.

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Ki-67 immunostaining showed a 30% proliferative index.

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Histological examination showed that the tumor was composed of spindle cells (H&E staining).

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MRI showed that the tumor was completely removed.

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Solitary fibrous tumors are very rare in the central nervous system. Immunohistochemical staining positivity for CD34 and Bcl-2 is strongly expressed in most solitary fibrous tumor. Surgical resection is the preferred treatment. Due to the small number of cases, the biological behavior and prognosis of this tumor need to be further explored.

Contact: Fardin Nabizadeh

Source: Zhu Y, -T, Liu Y, Chen L, -G, Song D, -P: Malignant Solitary Fibrous Tumor of the Right Cerebellum: A Case Report. Case Rep Neurol 2021;13:259-266. doi: 10.1159/000510844

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