A Rare Case of a Primary Unilateral Low-Grade Paratesticular Leiomyosarcoma in a 2 Years Old Dog

Abstract

A 2 years old dog was brought to the clinic with complains of testicular enlargement. The tissue was diffusely affected as confirmed by ultrasonographic examination, being the right testicle atrophied and the right epididymis enlarged, with loss of echotexture and presence of several anechogenic areas. The situation required the excision of the referred testicle and epididymis. Final diagnose made by histopathological analysis was primary unilateral low-grade paratesticular leiomyosarcoma. Scarce bibliography is found on this matter, with several cases reported on human, and none in dog. This case report is therefore an important milestone on the area of small animal oncology directly related to the reproductive tissue.

Keywords: dog; leiomyosarcoma; oncology; paratesticular; urogenital.

Figure 1

Testicle and epididymis, dog. Diagnostic ultrasonography of the epididymis (4 cm) with indication of one of the anechogenic areas (1.7 cm).

Figure 2

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).