A huge malignant solitary fibrous tumor of kidney: case report and review of the literature

Abstract

Virtual slidesThe virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1603694556107408.Solitary fibrous tumor (SFT) is a spindle cell neoplasm that rarely occurs in the kidney. Malignant SFT of the kidney is particularly rare. Here, we report a 66-year old woman with a right flank mass that has been proved clinically and radiographically. Grossly, the largest diameter of the mass were measured up to 23 cm, was poorly circumscribed. Approximately 80% of the neoplasm consisted of hyperchromatic and pleomorphic spindled cells surrounding staghornlike blood vessels. Tumor cells frequently had mitoses and necrosis. However, the remainder of the mass was composed of haphazard, storiform or short fascicular arrangements of spindle cells in a loose myxoid to fibrous stroma. Immunohistochemically, we observed diffusely strong CD34 staining and an 85% Ki-67 proliferative index. The tumor partly showed negative CD34 and a 20% proliferative index. To our knowledge, this is the largest malignant renal SFT in the reported literatures and shows an obviously high proliferative index.

Primary renal myxofibrosarcoma

“…No case with recurrence or metastasis has been reported. Malignant SFT shows decreased or absent expression of CD34 and CD99 in areas with marked atypia or dedifferentiation [33]. In addition, nuclear STAT6 immunoreactivity is a highly sensitive and specific marker of SFT [37].…”

“…Such a differential diagnosis is of clinical importance, because it involves lesions with extremely variable biologic behavior. Diagnosis may include myxoma with atypical features [3], aggressive angiomyxoma [28,29], low-grade fibromyxoid sarcoma (Evans tumor) [9], myxoid solitary fibrous tumor (SFT) [8,33] and myxoid liposarcoma [15].…”

A case of incidentally discovered solitary fibrous tumor of the kidney: A case study

“…Although about 15% of SFT of the kidney have been reported to be located in the renal capsule and 3% in the renal pelvis, the site of origin remains unknown in the majority of cases (5). The majority of SFT of the kidney are benign with about 14% of cases exhibiting malignant behavior (6,7). Like RCC, most of these tumors are asymptomatic and are incidentally discovered on radiologic evaluations.…”

Tumor Fibroso Solitário do Rim: Relato de Caso

“…Os métodos de imagens utilizados atualmente apenas sugerem a possibilidade de malignidade do tumor, pois não há características de imagem capazes de definir o potencial de benignidade ou malignidade dessa neoplasia. Portanto, o achado macroscópico e a análise histológica e imunohistoquímica da lesão são cruciais (ABDULLAH et al, 2013;WANG et al, 2014;ZONG et al, 2012). Pela escassez do tema na literatura, ainda não há um consenso no acompanhamento dos pacientes após o tratamento cirúrgico, mas, considerando o comportamento clínico duvidoso, podemos associar a variante benigna do tumor a uma neoplasia maligna metastática agressiva em potencial.…”

“…Pela escassez do tema na literatura, ainda não há um consenso no acompanhamento dos pacientes após o tratamento cirúrgico, mas, considerando o comportamento clínico duvidoso, podemos associar a variante benigna do tumor a uma neoplasia maligna metastática agressiva em potencial. Portanto, é sempre recomendado, quando possível, o tratamento cirúrgico (WANG et al, 2014;ZONG et al, 2012).…”