PMC6438921_01
Testicle and epididymis, dog. Diagnostic ultrasonography of the epididymis (4 cm) with indication of one of the anechogenic areas (1.7 cm).
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F1
A testicular ultrasonography was performed, major findings being: left testicle normal; right testicle atrophied; right epididymis presenting increased size (~4 cm), loss of normal echogenicity and presence of several anechogenic areas (<2 cm)(Figure 1).
Paratesticular tissue, dog. (a) Histopathological study of the sample. Proliferation of loose connective tissue composed of fusocellular cells with slight atypia (arrows). Hematoxylin and eosin (HE). (b) Actin immunohistochemical stain. This stain highlights the presence of numerous cells which show a fusiform morphology (arrowheads). (c) Ki67 immunohistochemical stain of the lesion. Presence of fusiform cells expressing this marker, indicating cell proliferation (arrowheads). (d) Vimentin immunohistochemical stain in which it is observed several immunolabeled cells disposed with diffuse pattern and morphology that points to a mesenchymal origin (arrowheads).
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F2
Surrounding the testis, an abundant proliferation of loose connective tissue was shown, formed by fusocellular cells with slight atypia, without necrosis and with few atypical mitosis (1/10 HPF) (Figure 2a). Immunohistochemical study of cell proliferation showed positivity to Actin (Figure 2b), Ki67 (5-10%) (Figure 2c) and Vimentin (Figure 2d), and negativity to Desmin, CD34 and AE1/AE3, which indicates a low-grade leiomyosarcoma, according to recent studies.