PMC5681726_01
Fine-needle aspirate from a renal mass in a cat. Poorly cellular and hemodiluted sample, with large three-dimensional clusters of moderately pleomorphic epithelial cells with variable nucleus/cytoplasmic ratio, moderate anisokariosis and prominent nucleoli (May-Grunwald-Giemsa stain; Bar=50 mum).
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F1
Cytologic samples were markedly hemodiluted, and displayed three-dimensional clusters of moderately pleomorphic epithelial cells with variable nucleus/cytoplasmic ratio, round to oval central nuclei with lacy reticular chromatin and prominent nucleoli (Fig. 1).
Gross appearance and histopathology of a feline renal mass. (A): Surgically resected kidney. The tumor mass has completely invaded cortex and medulla of the cranial pole; on section, the tumor tissue is non-capsulated and composed of multiple red lobules embedded in a dark red gelatinous tissue (Bar=2.5 cm). (B): Moderately pleomorphic epithelial cells arranged in irregular tubules and papillae, consistent with tubulo-papillary renal cell carcinoma (Hematoxylin and eosin stain; Bar=50 mum).
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F2
Grossly, the resected kidney revealed a 4 x 2.5 x 3 cm reddish mass at the cranial pole, non-capsulated, irregularly lobulated, invading both the cortex and the medulla (Fig. 2).
Immunohistochemistry for erythropoietin (EPO) expression. Diffuse and intense cytoplasmic immunostain for EPO in tumor cells (A: Bar=50 microm) and in tubular cells of non-neoplastic renal tissue adjacent to the carcinoma (B: Bar=100 microm).
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F3
In the case here reported, an intense and diffuse cytoplasmic positivity of tumor cells was demonstrated (Fig. 3).