De novo malignant solitary fibrous tumor of the kidney

Tsan-Yu Hsieh,Hui-Ping Chein,Wen-Hsiang Chen,Jim-Ray Chen,Siu-Chung Chen,Cheng-Cheng Hwang,Yi-Che Changchien,Liang-Che Chang

doi:10.1186/1746-1596-6-96

Tsan-Yu Hsieh, Hui-Ping Chein + Show 6 more

Open Access

https://doi.org/10.1186/1746-1596-6-96

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Abstract

The kidney is a relatively infrequent site for solitary fibrous tumor (SFT). Among the previously reported cases, only two cases of malignant renal SFT developing via dedifferentiation from a pre-existing benign SFT have been reported. Here we reported a case of de novo malignant renal SFT clinically diagnosed as renal cell carcinoma in a 50-year-old woman. The tumor was circumscribed but unencapsulated and showed obvious hemorrhagic necrosis. Microscopically, the tumor was composed of patternless sheets of alternating hypercellular and hypocellular areas of spindle cells displaying mild to moderate nuclear atypia, frequent mitoses up to 8 per 10 high power fields, and a 20% Ki-67 proliferative index. Immunohistochemical studies revealed reactivity for CD34, CD99 and vimentin, with no staining for all other markers, confirming the diagnosis of SFT. No areas of dedifferentiation were seen after extensive sampling. Based on the pathologic and immunohistochemical features, a diagnosis of de novo malignant renal SFT was warranted. Our report expands the spectrum of malignant progression in renal SFTs. Even though this patient has been disease-free for 30 months, long-term follow-up is still mandatory.

Highlights

The kidney is a relatively infrequent site for solitary fibrous tumor (SFT)
Backround Solitary fibrous tumors (SFTs) are distinctive mesenchymal tumors most commonly described as pleural-based lesions; they can develop at any extrapleural anatomic site [1]
* Correspondence: jimrchen@cgmh.org.tw 1Department of Pathology, Chang Gung Memorial Hospital, Keelung, Taiwan Full list of author information is available at the end of the article benign and only two cases of malignant renal SFTs developing via dedifferentiation or sarcomatous overgrowth from a pre-existing benign SFT have been reported [7,8]

Summary

Introduction

The kidney is a relatively infrequent site for solitary fibrous tumor (SFT). Among the previously reported cases, only two cases of malignant renal SFT developing via dedifferentiation from a pre-existing benign SFT have been reported. Microscopic features associated with malignancy in both intrathoracic and extrathoracic SFTs include nuclear atypia, increased cellularity and more than 4 mitoses per 10 high power fields [4,5]. * Correspondence: jimrchen@cgmh.org.tw 1Department of Pathology, Chang Gung Memorial Hospital, Keelung, Taiwan Full list of author information is available at the end of the article benign and only two cases of malignant renal SFTs developing via dedifferentiation or sarcomatous overgrowth from a pre-existing benign SFT have been reported [7,8].

Results

Conclusion