PMC3785379_01
A) Abdominal computed tomography demonstrated the presence of a solid encapsulated mass with nonuniform internal structure about 11 x 9 cm in diameter, compressing the right kidney to the caudal side; B) contrast-enhanced CT showed a tumor with early enhancement in mainly dorsal side of the tumor.
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Abdominal computed tomography (CT) demonstrated the presence of a solid encapsulated mass with nonuniform internal structure about 11 x 9 cm in diameter, compressing the right kidney to the caudal side (Fig. 1a). Contrast-enhanced CT showed a tumor with some early staining in mainly dorsal side of the tumor, suggesting that the tumor feeding was supplied by the feeders from lumbar muscles such as latissimus dorsi muscle, quadratus lumbar muscle, and psoas major muscle (Fig. 1b).
A) Magnetic resonance imaging demonstrated a tumor that had relatively smooth margin in the retoperitoneum exhibiting mainly high intensity on T1 weighting; B) T2-weighted image showed a high signal intensity tumor with low signal intensity area inside.
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On magnetic resonance imaging (MRI), the large tumor having relatively smooth margin in the retoperitoneum exhibited mainly high intensity on both T1 (Fig. 2a) and T2 weighting (Fig. 2b).
Surgical specimen: A) Macroscopic findings showed a well-circumscribed and encapsulated elastic hard tumor, 12 x 10 x 9 cm in diameter; B) Cross section showed yellowish fibrous lobulated solid mass with a whorled or nodular appearance.
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Macroscopic findings showed a well-circumscribed and encapsulated elastic hard tumor, 12 x 10 x 9 cm in diameter, with partly infiltrative growth into latissimus dorsi muscle (Fig. 3a). Cross section of specimens showed yellowish fibrous lobulated solid mass with a whorled or nodular appearance (Fig. 3b).
Histological findings (H&E staining): A) The tumor consisted of spindle-shaped cells with patternless pattern and hemangiopericytomatous appearance (x40); B) The tumor cells had oval or fusiform nuclei with fine chromatin and indistinct cytoplasm (x200).
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Pathological examination revealed that the tumor was composed of spindle-shaped cells with varied cellular intensity, consisting of a mixture of haphazard or interlacing fascicular arrangements of spindle-shaped cells and collagenous matrix with patternless pattern and hemangiopericytomatous appearance (Fig. 4a). The tumor cells had oval or fusiform nuclei with fine chromatin and indistinct cytoplasm (Fig. 4b).
Immunohistochemical staining: A) CD34; B) vimentin; C) bFGF.
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Immunohistochemical staining was positive for CD34 (Fig. 5a), vimentin (Fig. 5b), and basic fibroblast growth factor (bFGF) (Fig. 5c) and negative for CD31, cytokeratin, desmin, S-100p, smooth muscle actin,