Splenic malignant mesenchymoma in a dog – immunophenotypic features and clinicopathological ramifications: a case report

Abstract

A 13-year-old spayed bitch was referred for evaluation of an abdominal distension with a palpable, continuously growing mass. Abdominal ultrasonography revealed a 30 × 20 cm mass directly connected to the spleen. Surgical exploration confirmed the sonographic diagnosis with adhesions to the omentum and the liver. Pathohistological samples revealed well differentiated adipose tissue and variably differentiated collagenous and myxomatous tissue. Immunohistochemically, vimentin and in some regions alpha smooth muscle actin were expressed indicating smooth muscle differentiation. The results support the diagnosis of a malignant mesenchymoma composed of liposarcoma, mixosarcoma and leiomyosarcoma. No local recurrence or metastasis occurred during a nine month follow-up. So far, only two pathological retrospective studies describing the common prevalence and properties of canine splenic malignant mesenchymomas were found in the literature. However, this rare tumor entity has to be considered as a differential diagnosis in cases of large splenic masses.