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Year : 2018  |  Volume : 14  |  Issue : 12  |  Page : 1217-1219

Malignant solitary fibrous tumor of the kidney with liver metastasis: A case report and literature review

Department of Medical Imaging, Shanghai Gongli Hospital, Shanghai 200135, China

Date of Web Publication11-Dec-2018

Correspondence Address:
Bingcang Huang
Department of Medical Imaging, Shanghai Gongli Hospital, Miaopu Road No. 219, Pudong New Area Shanghai 200135
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0973-1482.204885

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 > Abstract 

Solitary fibrous tumor (SFT) is a rare spindle cell soft tissue tumor which is rarely encountered in the clinical setting and imaging findings are nonspecific, mainly occurring in the tissue structure of the serosa. However, there is very little report on SFT originating in the kidney in the medical literature. We report a case of SFT with liver metastasis in an adult female and discuss the pathological features as it appears in our case.

Keywords: Computed tomography scan, mesenchymal tumor, solitary fibrous tumor

How to cite this article:
Zhang N, Zhou D, Chen K, Zhang H, Huang B. Malignant solitary fibrous tumor of the kidney with liver metastasis: A case report and literature review. J Can Res Ther 2018;14, Suppl S5:1217-9

How to cite this URL:
Zhang N, Zhou D, Chen K, Zhang H, Huang B. Malignant solitary fibrous tumor of the kidney with liver metastasis: A case report and literature review. J Can Res Ther [serial online] 2018 [cited 2020 Jan 23];14:1217-9. Available from: http://www.cancerjournal.net/text.asp?2018/14/12/1217/204885

 > Introduction Top

Solitary fibrous tumor (SFT) is a rarely encountered primary mesenchymal tumor, which was first described by Klemperer and Rabin in 1931 and is currently recognized as originating from CD34-positive dendritic interstitial cells.[1],[2] There is very little report on SFT originating in the kidney. Malignant renal SFT with liver metastasis is especially rare. Here, we discussed such a case at our center.

 > Case Report Top

A 62-year-old female presented with persistent left flank pain was admitted on January 9, 2015. She received meningioma surgery 10 years ago. Computed tomography (CT) plain scan showed an oval-shaped and low-density mixed mass in the posterior of the left kidney, about 6.5 cm × 6.0 cm × 5.5 cm, with CT value 40 HU. Enhanced CT scan in period of cortex and medulla displayed the nonhomogeneity of the mass, non-enhancement of the necrosis, along with an envelope, which was visible during the excretory phase. CT angiography showed that both the renal artery and renal vein did not have any filling defect. An oval-shaped mass, about 5.5 cm × 5.0 cm × 4.0 cm, was seen in the upper inner section of the left lobe of the liver, with lobes at the edges. CT value was 12 HU for unenhanced cystic part and 39 HU for solid nodules part. After enhancement, the solid part was intensified. Preoperative diagnosis and CT results: (1) Renal malignant tumor in the upper pole of the left kidney. (2) Cystadenocarcinoma in the left lobe of the liver.

The patient underwent laparoscopic radical nephrectomy under general anesthesia.

Operative findings

A solid mass, about 6 cm in diameter, was found in the upper left kidney. The capsule and Gerota's fascia were not invaded.

Pathological examination

At the upper left kidney, malignant spindle cells were seen with necrosis, and blood vessels clustered. 14 mitoses/50 HPF was found in some areas. Immunohistochemistry results: CD99 (−), CK (−), VIM (100% +++), S100 (90% ++), Bcl-2 (−), CD34 (100% +++), Ki-67 (about 5% positive), and epithelial membrane antigen (EMA) (80% + ~ ++). EMA was positive, fluorescence in situ hybridization (FISH) detection of SYT–SSX fusion gene was thus performed. SS 18 separate probe in dual color fluorescence in situ hybridization (FISH 2015 327) show no SYT gene isolation, suggesting negative FISH test results. Pathological diagnosis results was malignant SFT.

Partial hepatectomy was performed two months later. The tumor was found in the left hepatic lobe near the second hepatic hilum, about 4.7 cm × 4.3 cm × 4.0 cm with partial invasion of section VIII. The boundaries were clear, and the tumor was encapsulated. No enlarged hilar lymph nodes were seen and no tumor thrombus in the main portal vein and or the left and right branches. Pathological examination results: abundant spindle cell tumors with 31 mitoses/50 HPF. No tumor involving the liver margin, no hardening of the surrounding liver tissue. Immunohistochemistry results: CD34 (+++), CK (−), VIM (+++), Bcl-2 (−), calponin (+/−), CD99 (−) superior mesenteric artery (SMA) (−), Des (−), CD68 (histiocytes +), S-100 (10% +), and Ki-67 (20% positive) [Figure 1]a, [Figure 1]b, [Figure 1]c, [Figure 1]d, [Figure 1]e, [Figure 1]f. Pathological diagnosis was malignant SFT metastasis.
Figure 1: (a) Clear border with fibrous capsule wrapped, necrosis was found in the surroundings. (b) Tumor cells were short shuttle-like with less cytoplasm, even nuclear chromatin. The arrow indicates mitotic figures. (c): CD34+. (d): CD99+. (e): Ki-67 (about 5% positive). (f): Vimentin+

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Initially, the patient admitted to hospital with abdominal pain and other symptoms of renal tumor compression. The decision of performing the partial hepatectomy and nephrectomy separately was made by the patient and the patient's family by considering the age, physical condition, and operative tolerance of the patient. The patient and patient's family were informed of the surgical treatment modalities, and the decision was made based on their interest in preferring relevant authority hospital and specialists. The pathological examination was performed after surgery. The patient did not receive any adjuvant chemotherapy pre- and post-surgery, and no complication was detected during perioperative period. The follow-up after surgery has been continued by the author of this paper. Postoperative recovery was well, and no recurrence and metastasis were found in the liver or kidney until the time of manuscript submission.

 > Discussion Top

SFT patients have nonspecific clinical signs and symptoms; they are likely to have complete tumor capsule without invasive growth, so most patients are diagnosed following a physical examination checkup or press pain due to slow growth of the tumor.[3] The patient discussed in this report was diagnosed following complaints of low back pain.

Diagnosis of renal SFT is mainly based on the histopathological and immunohistochemical findings. The tumor has clear boundaries, and the cross section of the tumor is gray or grayish yellow with hard texture and no hemorrhage or necrosis. Immunohistochemistry is often positive for CD34, CD99, and Bcl-2. In a few cases, SMA is expressed while S-100 protein, desmin, HMB45, EMA, and CK are mostly negative.[3] Strong positive expression of CD34 was recognized as a necessary diagnosis condition of SFT,[4] but CD34 can also be expressed in other spindle cell tumors such as skin fibrosarcomas. Therefore, CD34 is not specific to SFT.[5] Some studies suggested that immunohistochemical diagnosis of SFT cannot rely on a single indicator, other indicators must be combined.[6] In our case, EMA expression was positive, which is rarely seen in SFT patients. The possibility of synovial sarcoma was excluded by doing FISH analysis for SYT–SSX fusion gene.

SFT lacks characteristic manifestation on radiographic images. Due to its low incidence, no systematic theory can be used as references. Chen et al.[7] reported that SFT is shown as low-density and even soft-tissue mass. After enhancement, the tumor boundaries were very clear, and there was a gradual trend of heterogeneous intensification. Zeng et al.[8] found that on the MRI scan, T1WI mainly shows low signal intensity and on T2WI low or mid-low mixed signal intensity. The CT scan for this patient [Figure 2]a showed that the left kidney pole had a slightly lobulated low-density mass, with nonuniform density within the mass, and was protruding outside the kidney; nonenhanced CT value averaged 41 HU. After enhancement [Figure 2]b, [Figure 2]c, [Figure 2]d, the cortical lesions were significantly rapidly intensified, sustained intensification of medulla also occurred and the contrast withdrew during excretion phase. SFT exhibits a “fast-in and slow-out” pattern when enhanced.[9] Sagittal reconstruction [Figure 2]e shows that the renal cortex was compressed, which is in accordance with the knowledge that renal SFT originates from the kidney capsule from undifferentiated mesenchymal cells.[10] In our case, the patient presented a solitary space-occupying lesion in the liver [Figure 3]a, [Figure 3]b, [Figure 3]c. The CT scan showed low-density mass with solid nodules at the edge, and the nonenhanced CT value for the cystic part was 16 HU. CT value of solid part was 44 HU.
Figure 2: (a) Computed tomography scan shows low-density lesion in the upper pole of the left kidney. (b-d) Three phases scanning. The solid part of the lesion is obviously intensified. Cortical phase computed tomography value was 83 HU, medullary phase computed tomography value was 92 HU, and excretory phase computed tomography value was 66 HU. The necrotic part was not intensified, and the boundaries were clear. (e) Computed tomography sagittal reconstruction showed that the upper pole of the left kidney was compressed, and the cortex of the kidney was whole and not interrupted

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Figure 3: (a) Computed tomography scan shows a cystic solid space-occupying lesion in the upper part of the right lobe of the liver. The computed tomography value of the cystic part was 16 HU that of the solid nodules was 44 HU. (b) During the enhanced arterial phase, the cystic part of the lesion was not intensified, and the solid nodular part was obviously intensified. The computed tomography value was 124 HU. (c) The computed tomography value of the enhanced venous phase was 109 HU. The contrast agent withdrew during the delayed phase, and the average computed tomography value was 71 HU

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Renal SFT needs to be differentiated with renal hematoma, renal pelvis malignant tumors, and renal benign tumors.[10] In several cases, it was initially misdiagnosed as renal cell carcinoma, carcinoma of the renal pelvis, or angiomyolipoma. The case in this study was misdiagnosed as renal cell carcinoma before the surgery.

Thus, we propose that CT 3D reconstruction was useful for the mass location clearly, when the lesion can be compressed to the kidney, but not invaded, may indicate it originating from renal interstitial. Use of combined phase enhanced CT scan allows us to determine the localization and characterization of the lesion.

Financial support and sponsorship

Financial support and sponsorship was provided by:

  1. Innovation funds for development of science and technology in new PuDong area, Grant No.: PKJ2014-Y20
  2. Academic Leaders of the Health System of New Pudong Area, Grant No.: PWRd2011-05
  3. Shanghai Municipal Health and Family Planning Foundation, Grant No: 201440458.

Conflicts of interest

There are no conflicts of interest.

 > References Top

Jadczak P, Guz W, Kaznowska E, Ramotowski R, Szalacha-Tarała E, Górecki A, et al. solitary fibrous tumour of the pleura-cases analysis, Pol J Radiol 2014;79:368-73.  Back to cited text no. 1
Hanai S, Okishio N. Malignant peritoneal mesothelioma of the prostate: A case report. Hinyokika Kiyo 1986;32:1725-30.  Back to cited text no. 2
Huang HP, Fu WJ, Liu DY, Yang ZB, Mo ZN. Clinical pathological characteristics and diagnosis of solitary fibrous tumor of the kidney. J Clin Urol 2015;30:489-91.  Back to cited text no. 3
Hirano D, Mashiko A, Murata Y, Satoh K, Ichinose T, Takahashi S, et al. A case of solitary fibrous tumor of the kidney: An immunohistochemical and ultrastructural study with a review of the literature. Med Mol Morphol 2009;42:239-44.  Back to cited text no. 4
Ettore M, Giovanni C, Francesco B, Roila F. Renal malignant solitary fibrous tumor with single lymph node involvement: Report of unusual metastasis and review of the literature. Onco Targets Ther 2014;7:679-85.  Back to cited text no. 5
Xu YT, Zhang L. Clinical and pathological features of 10 cases of solitary fibrous tumor. Acta Acade Med Xuzhou 2013;33:27-30.  Back to cited text no. 6
Chen J, Song YR, Zhang SH. CT features of primary malignant solitary fibrous tumor of the kidney. Chin J Med Imaging Technol 2015;31:105-9.  Back to cited text no. 7
Zeng XL, Fan CS, Qin HW, Chen YL, He XZ, Tan GM, et al. Clinical manifestation and imaging features of solitary fibrous tumor: A report of 3 cases and review of the literature. J Pract Med Imaging 2006;7:13-5.  Back to cited text no. 8
Du EZ, Tan XJ, Zhang HK, Du HQ, Tu JH. Imaging features of solitary fibrous tumors in abdomen and pelvis. Chin J Med Imaging 2014;22:369-71, 374.  Back to cited text no. 9
Li SJ, Chen YX, Yuan CY. Imaging diagnosis of solitary fibrous tumor of the kidney. Radiologic Practice 2007;22:591-93.  Back to cited text no. 10


  [Figure 1], [Figure 2], [Figure 3]


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