PMC6287080_01
Contrast enhanced computed tomography abdomen showed large lobulated necrotic hypodense enhancing lesion involving part of retroperitoneal space.
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Gross image of a renal primitive neuroectodermal tumor. This specimen is notable for a variegated appearance. Select areas of the tumor feature a tan/brown or dark brown/red coloration, whereas other sections of the tumor feature a more yellow appearance, helping to illustrate the range of coloration observable on gross examination. This specimen is also notable for its lobulated appearance.
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Gross examination of the specimen sent to us revealed a soft tissue mass measuring about 47 x 42 x 37 mm, cut surface of which revealed an encapsulated creamy to brownish mass with lobulated and variegated appearance with solid and necrotic areas with foci of calcification (Fig. 2).
A, Hematoxylin and eosin features of the tumor (original magnification 40 x): sheets of poorly differentiated, monotonous, ovoid cells, with a high nuclear to cytoplasmic ratio. Homer-Wright rosettes were common. B, Tumor cells with necrotic areas and foci of calcifications .C, Immunoperoxidase for CD99 (40x) showed predominantly membranous staining of tumor cells composed of small round cells with round nuclei and scant cytoplasm arranged in cohesive lobules. D, Immunoperoxidase for ACTH (10x) showed Diffuse cytoplasmic staining of tumor cells.
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The tumor cells comprised of small cells with round vesicular nuclei, inconspicuous nucleoli, scanty eosinophilic cytoplasm with frequent homer wright rosettes and pseudorosettes (Fig. 3). Also, there were focal expression of synaptophysin and ACTH (Fig. 3).