Seminoma
Keywords: stallion, equine, seminoma, testicle, neoplasia
Image size: 1437 x 2079px
An 18 year old stallion with a seminoma in his left testicle. The stallion was presented because of remarkable enlargement (A) of the left testicle. Asymmetry due to the enlargement of this testicle was more evident in a lateral view than a caudal view. The appearance on ultrasound (B) of the seminoma (s) showed irregular masses of variable echodensity compared to normal (n) testicular parenchyma in the same testicle.
A needle biopsy was performed, providing a diagnosis of a seminoma and leading to hemicastration of the affected testicle. The site of the needle biopsy (C) was obvious on the visceral surface of the tunica vaginalis of the testicle. On cut surface of the removed testicle (D) the seminoma was obvious, as were areas of avascular necrosis (orange arrows). The normal tissue (n) seen on ultrasound and the seminoma (s) are clearly visible here as well.
Seminomas are the most common testicular tumors in stallions (Leydig cell and Sertoli cell tumors also occur) and should always be a differential diagnosis in older stallions with testicular asymmetry. As in other species, seminomas appear to have a higher prevalence in cryptorchid animals then normal animals. Fortunately, testicular neoplasms in stallions usually do not metastasize (although metastasis has been well documented) and they are rarely fatal; this, in contrast to the situation in humans.
