Case Report Solitary fibrous tumor of the central nervous system: report of 2 cases and review of literature

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1 Int J Clin Exp Pathol 2014;7(6): /ISSN: /IJCEP Case Report Solitary fibrous tumor of the central nervous system: report of 2 cases and review of literature Ge Wen 1*, Meifang Li 1*, Lijun Xu 2, Peiqian Hu 1, Xin Liao 3, Chuang Lin 4, Liang Zhao 2,4 1 Department of Imaging Center, Nanfang Hospital, Southern Medical University, Guangzhou, China; 2 Department of Pathology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China; 3 Department of Radiology, Nanfang Hospital, Southern Medical University, Guangzhou, China; 4 Department of Pathology, Nanfang Hospital, Southern Medical University, Guangzhou, China. * Equal contributors. Received April 15, 2014; Accepted May 27, 2014; Epub May 15, 2014; Published June 1, 2014 Abstract: Solitary fibrous tumors (SFTs) rarely occur in the central nervous system (CNS). Involvement of the brainstem and pineal gland is rarely recorded. Herein, we represent 2 cases of SFTs and firstly report SFT of the pineal gland. Cranial MR imaging showed isointense to hypointense signal intensity, and marked enhancement. Microscopically, the tumors showed characteristic patternless-pattern architecture. Elongated tumour cells formed fascicles alternating with hypocellular densely collagenous stroma. Immunohistochemistry for CD34, BCL2, and CD99 favors the definitive diagnosis of SFT. It is difficult to predict prognosis in patients with intraventricular SFT. In general, complete surgical resection may offer the best chance of a favorable clinical outcome. Keywords: Solitary fibrous tumor, central nervous system, immunohistochemistry, magnetic resonance imaging, CD34 Introduction Solitary fibrous tumors (SFTs), rare mesenchymal spindle cell neoplasms, are frequently arising from the pleural cavity. It rarely occurs in extrapleural sites like upper respiratory tract, lung, nasal cavity, paranasal sinuses, orbits, mediastinum, major salivary glands, breast, meninges, liver and urogenital organs [1, 2]. The central nervous system (CNS) SFT was firstly described by Carneiro et al. in 1996 [3]. Approximately a hundred and odd cases have been reported previously at various sites within the CNS. Involvement of the brainstem and pineal gland is rarely recorded. Herein, we represent 2 cases of SFTs and firstly report SFT of the pineal gland: we discuss their clinical, imaging feature, histological features, and differential diagnosis. Case report Case one A 44-year-old female presented with a five-day history of headache and dizziness. Her neurologic examination was normal but MRI demonstrated a cm round-like mass with clear margin in pineal region. Solid portions of mass showed low signal on T1WI (Figure 1A) and high signal on T2WI (Figure 1B) with markedly enhancement on contrast, while cystic portions presented as multiple cystiform long T1 and long T2 signal intensity, not enhanced on contrast. Adjacent brain tissue was lamellar long T1 and slightly long T2 signal intensity meaning edema and markedly enhanced on contrast (Figure 1C). Imaging findings suggested a germinoma. The patient underwent pineal region lumpectomy. Pathologic examination revealed a spindle cell tumor with a patternless-pattern and areas of dense collagen deposition. Tumor composed of cellular and paucicellular areas. In the cellular areas, the tumor showed interlacing fascicles of spindle-shaped cells with moderate amount of cytoplasm and oval to elongated nuclei exhibiting variable pleomorphism (Figure 2A). No mitotic activity was noted. In the paucicellular areas, dense bands of collagen were seen separating the cells (Figure 2B). The stroma was

2 Figure 1. Brain MRI images of two cases. A: T1-weighted axial MRI image of case one. B: T2-weighted axial MRI image of case one. C: Gadolinium-enhanced T1-weighted axial MR image of case one. D: T1-weighted axial MRI image of case two. E: T2-weighted axial MRI image of case two. F: Gadolinium-enhanced T1-weighted axial MR image of case two. myxoid in areas and thin vascular channels were present. Immunohistochemically, tumor cells showed strongly positive for vimentin and CD34, weakly positive for CD99, partially positive for Bcl-2 and S-100 and negative for EMA (Figure 2C). Ki-67 immunostaining showed a 5% proliferative index. The patients made an excellent recovery with a normal examination and no evidence of recurrence six months after surgery. Case two A 52-year-old male presented with numbness and weakness in all four extremities for one week. Physical examination showed hypalgesia, hypothermesthesia and hypopselaphesia of the whole body. Brain MRI revealed a cm fusiform mass with clear margin in front of the medulla oblongata, was showed isointense and low signal on both T1WI (Figure 1D) and T2WI (Figure 1E). It was markedly heterogeneous enhanced after enhancement, in which emerged dot-strip non-enhancement, and the meninges in front of cervical spinal cord were markedly enhanced so that the lesion was separated from the medulla oblongata (Figure 1F). The smaller medulla oblongata was compressed and displaced to the right and backward. The imaging appearance raised a differential diagnosis including meningioma and neurilemmoma. The patient underwent brainstem lumpectomy. In the histopathological examination, pattern variation was observed. Elongated tumour cells formed fascicles alternating with hypocellular densely collagenous stroma, similar to morpho Int J Clin Exp Pathol 2014;7(6):

3 Figure 2. Histopathological and immunohistochemical images of two cases. (A & B) The tumor of case two showed a spindle cell tumor with a patternless-pattern and areas of dense collagen deposition. Tumor composed of cellular (A) and paucicellular (B) areas. (C) Tumor cells showed strongly positive for CD34. (D & E) Elongated tumour cells formed fascicles alternating with hypocellular densely collagenous stroma. (F) Tumor cells were strongly positive for CD34. logical features of case two (Figure 2D & 2E). Immunohistochemically, the tumor cells were strongly positive for vimentin and CD34, weakly positive for S-100 and negative for EMA (Figure 2F). Ki-67 was expressed by less than 1% of cells. He has been lost to follow-up from three months after operation. Discussion SFT is a relatively new entity and our understanding of its nature is still limited. Although pleural SFT is still the most common, SFT has been described in various extrapleural sites, including soft tissues, the abdominal cavity, and the CNS [4]. SFTs can present in various locations with the CNS [5-8] and can be metastatic to visceral organs [9-11]. Herein, we reported 2 cases of SFTs in the CNS. To our best knowledge, SFT of the pineal gland has not been previously described. The classic histologic features combined with immunohistochemistry are helpful in reaching a correct diagnosis. The characteristic histologic features of SFT include the so-called patternless-pattern of spindle cells, hemangiopericytoma-like pattern of vascularity, and thick strands of stromal collagen. Alternating hypo- and hypercellular areas is another important clue on low-power examination. Intense immunoreactivity for CD34 and Bcl-2 favors the diagnosis of SFT. Hypo- and hypercellular areas, collagenized stroma and strong CD34 positivity favored the diagnosis of SFT in the present case. SFTs are difficult to distinguish from hemangiopericytoma and the general consensus in the nonurologic community is to combine those 2 entities into 1 entity. In the nervous system, however, the World Health Organization committee on the classification of tumors still maintains that those entities are separate. Hemangiopericytomas (HPCs) are remarkable for their characteristic thin-walled, branching or staghorn blood vessels. Although cellularity is variable, HPCs are often composed of closely packed, randomly oriented cells with irregular, carrot-shaped nuclei. The CD34 staining for SFT is usually strong and diffuse, whereas that of hemangiopericytoma is inconsistent and patchy. No specific molecular markers are known so far for SFTs. In contrast to soft tissue SFTs, within the CNS, HPCs are recognized as aggressive tumors with high rates of recurrence and metastasis [12]. However, Corinne et al. found overlapping pathological features and 3446 Int J Clin Exp Pathol 2014;7(6):

4 common prognostic factors between SFT and HPC, suggesting that they belong to the same spectrum of tumors [13]. It is difficult to predict prognosis in patients with intraventricular SFT given the relative rarity of the lesion in the CNS, particularly at this site, and the limited information available regarding long-term outcomes. Metellus et al. showed a 50% recurrence rate over a median follow-up period of 45 months with a statistically significant association to incomplete surgical resection [14]. Histological features such as necrosis, hypercellularity and mitoses did not affect the rate of recurrence. A high proliferation index should be considered as a prognostic parameter. Michele et al. advocated inclusion of high Ki-67 (i.e., >5%) as an adverse prognostic parameter in assessing the prognosis of SFT of the CNS [15]. In the study, the tumor of case two showed hypercellularity and high Ki-67 (10%) index. There have still been no recorded recurrences. Therefore, in keeping with SFT at other sites in the CNS, complete surgical resection may offer the best chance of a favorable clinical outcome. In conclusion, SFTs are rare in the central nervous system, so this diagnosis is usually overlooked by physicians. Careful radiological and histopathological examination is required to arrive at an accurate diagnosis. Total tumour removal can usually be achieved with an appropriate surgical technique. Disclosure of conflict of interest None. Address correspondence to: Dr. Liang Zhao, Department of Pathology, Nanfang Hospital, Southern Medical University, Guangzhou, China. Tel: ; Fax: ; liangsmu@gmail.com References [1] Chan JK. Solitary fibrous tumour-everywhere, and a diagnosis in vogue. Histopathology 1997; 31: [2] Du L, Rao G, Wang H, Li B, Tian W, Cui J, He L, Laffin B, Tian X, Hao C, Liu H, Sun X, Zhu Y, Tang DG, Mehrpour M, Lu Y and Chen Q. CD44- positive cancer stem cells expressing cellular prion protein contribute to metastatic capacity in colorectal cancer. Cancer Res 2013; 73: [3] Carneiro SS, Scheithauer BW, Nascimento AG, Hirose T and Davis DH. Solitary fibrous tumor of the meninges: a lesion distinct from fibrous meningioma. A clinicopathologic and immunohistochemical study. Am J Clin Pathol 1996; 106: [4] Goodlad JR and Fletcher CD. Solitary fibrous tumour arising at unusual sites: analysis of a series. Histopathology 1991; 19: [5] Donnellan RB, Govender D, Chite SH and Landers AT. An unusual presentation of solitary fibrous tumor. Spine (Phila Pa 1976) 2000; 25: [6] Kim KA, Gonzalez I, McComb JG and Giannotta SL. Unusual presentations of cerebral solitary fibrous tumors: report of four cases. Neurosurgery 2004; 54: ; discussion [7] Miyashita K, Hayashi Y, Fujisawa H, Hasegawa M and Yamashita J. Recurrent intracranial solitary fibrous tumor with cerebrospinal fluid dissemination. Case report. J Neurosurg 2004; 101: [8] Hashimoto K, Miyamoto K, Hosoe H, Kawai G, Kikuike K, Shimokawa K, Suzuki N, Matsuo M, Kodama H and Shimizu K. Solitary fibrous tumor in the cervical spine with destructive vertebral involvement: a case report and review of the literature. Arch Orthop Trauma Surg 2008; 128: [9] Munoz E, Prat A, Adamo B, Peralta S, Ramon y Cajal S and Valverde C. A rare case of malignant solitary fibrous tumor of the spinal cord. Spine (Phila Pa 1976) 2008; 33: E [10] Ng HK, Choi PC, Wong CW, To KF and Poon WS. Metastatic solitary fibrous tumor of the meninges. Case report. J Neurosurg 2000; 93: [11] Gessi M, Gielen GH, Roeder-Geyer ED, Sommer C, Vieth M, Braun V, Kuchelmeister K and Pietsch T. Extracranial metastasizing solitary fibrous tumors (SFT) of meninges: histopathological features of a case with long-term followup. Neuropathology 2013; 33: [12] Guthrie BL, Ebersold MJ, Scheithauer BW and Shaw EG. Meningeal hemangiopericytoma: histopathological features, treatment, and long-term follow-up of 44 cases. Neurosurgery 1989; 25: [13] Bouvier C, Metellus P, de Paula AM, Vasiljevic A, Jouvet A, Guyotat J, Mokhtari K, Varlet P, Dufour H and Figarella-Branger D. Solitary fibrous tumors and hemangiopericytomas of the meninges: overlapping pathological features and common prognostic factors suggest the same spectrum of tumors. Brain Pathol 2012; 22: [14] Metellus P, Bouvier C, Guyotat J, Fuentes S, Jouvet A, Vasiljevic A, Giorgi R, Dufour H, Grisoli F and Figarella-Branger D. Solitary fibrous 3447 Int J Clin Exp Pathol 2014;7(6):

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