PMC3919790_01
Ultrasonography of the cyst four years previously.
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Further investigation revealed a right renal cortical cyst, 29 mm in diameter, by ultrasonography (USG) (Fig. 1).
Ultrasonography of the cyst prior to surgery.
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USG (Fig. 2). The cyst was more complex and, in the base of the mass, a semilunar hyper echoic region was identified that may belong to the solid component of the tumor lesion. Abdominal tomography showed a semi-solid, exophytic situated cyst, averaging 40x35 mm in size, located at the posterior aspect of the inferior pole of the right kidney (Fig. 3). Upon admission to the hospital, the patient's hemoglobin (Hgb) level was 13 g/dl, white blood cell (WBC) count was 6.16x103/mm3, red blood cell (RBC) count was 4.36x103/mm3, hematocrit (HCT) result was 39.7% and platelet (PLT) count was 244x103/mm3 (Table I).
Computerized tomographic appearance of the cyst prior to surgery. Punctate calcification consistent with extramedullary hematopoiesis is circled.
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USG (Fig. 2). The cyst was more complex and, in the base of the mass, a semilunar hyper echoic region was identified that may belong to the solid component of the tumor lesion. Abdominal tomography showed a semi-solid, exophytic situated cyst, averaging 40x35 mm in size, located at the posterior aspect of the inferior pole of the right kidney (Fig. 3). Upon admission to the hospital, the patient's hemoglobin (Hgb) level was 13 g/dl, white blood cell (WBC) count was 6.16x103/mm3, red blood cell (RBC) count was 4.36x103/mm3, hematocrit (HCT) result was 39.7% and platelet (PLT) count was 244x103/mm3 (Table I).
Fibrous cyst wall demonstrating the tumor focus (hematoxylin and eosin; magnification, x2).
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Histopathologically, the outer aspect of the cyst revealed atrophic tubules and sclerotic glomeruli consistent with the intraparenchymal location of the cyst (Fig. 4).
In spite of the clear cell type, in which the cytoplasm appears empty (not stained) due to glycogen content, the cell cytoplasm in this tumor contains mitochondria, which are stained by H&E (grey) (magnification, x20).
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The epithelial lining of the cyst consisted of cells with monotonous nuclei and oncocytic cytoplasm (Fig. 5).
Different immunohistochemical expression of the tumor cells and immunohistological characteristics of the focus (right side). Cells negative for MPO were identified as erythroblasts. Circle indicates megakaryocytes [diffuse cytoplasmic staining of CK7 and CK8 at magnification x10; membranous (honey-comb pattern) staining of E-cadherin at magnification x20; negative staining of CD10 at magnification x10; MPO, magnification x20; CD61, magnification x10]. MPO, myeloperoxidase.
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Tumor cells were negative for clear cell type RCC markers, CD10 and vimentin, and positive for chromophobe cell type RCC markers, E-cadherin and CK7, as well as oncocytic cell markers, CK8 and CK18 (Fig. 6).
Bone trabeculae and cyst wall (H&E, x4). The inset shows the following bone marrow cells: 1, erythroblasts; 2, myeloid series; and 3, megakaryocytes (H&E; magnification, x20). H&E, hematoxylin and eosin.
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An examination of the mural nodule revealed bone trabeculae with evident BM elements (Fig. 7), which were positive for the erythroblast (glycophorin), myeloid (myeloperoxidase) and megakaryocytic (CD61) markers (Fig. 6).