Liposarcoma mixoide splenico primario in due cani

Nonvascular-nonlymphoid (NVNL) sarcomas represent 23-34% of canine primary splenic sarcomas. Splenic liposarcoma accounts for 2-6% of NVNL. Liposarcomas commonly raise in the subcutaneous fat and are classified in three histologic variants: differentiated, myxoid and pleomorphic. No histological subtyping has been described for splenic cases. Two dogs, a mongrel 8-year-old male and a Bouledogue 15-year-old female presented with a splenic round mass of 15 cm and a bilobed mass of 7,5 x 6 cm. On cut section both tumours had a translucent, gelatinous and mucous surface. Histology, histochemistry, immunohistochemistry and electron microscopy (EM) (1 case) were performed. Histology was characterized by neoplastic cells organized in loose bundles admixed with abundant extracellular matrix. Neoplastic cells were spindle, with lightly eosinophilic cytoplasm occasionally containing sharply demarcated clear vacuoles. Mitotic index was 0,1 and 1,6, respectively. Morphology was consistent with myxosarcoma of grade II in both cases. Matrix was Alcian-Blue positive and PAS negative. Vacuoles were Oil red O positive. Neoplastic cells were vimentin positive and actin, desmin, Factor VIII, S100 negative. In one case, EM evidenced adipose cells at different maturative stages. Two months post-splenectomy the first dog was euthanized and necropsy revealed disseminated hepatic metastases and lymph node involvement. Ancillary techniques were necessary for the diagnosis of myxoid liposarcoma.[...]