Spontaneous primary splenic liposarcoma in a guinea pig ( Cavia porcellus )

Abstract Spontaneous splenic tumours are rare in guinea pigs, although recent reports have described primary splenic haemangiosarcoma in this species. This is the first case of spontaneous splenic liposarcoma in a 6‑year‑old entire female guinea pig ( Cavia porcellus ), which presented with lethargy, anorexia and abdominal distension. A palpable round abdominal mass was detected, and ultrasound examination confirmed a 7 cm soft‐tissue splenic lesion. A total splenectomy was performed, and the excised tissue underwent histopathological and immunohistochemical evaluation. Histopathology identified a mesenchymal neoplasm characterised by spindle‑shaped cells with large optically empty vacuoles, compatible with liposarcoma, while immunohistochemistry confirmed the diagnosis, showing vimentin positivity and pancytokeratin and S100 negativity. No metastatic lesions were identified in other organs. Despite surgical intervention, the animal's clinical condition deteriorated, and euthanasia was performed. Primary splenic liposarcoma has not previously been described in guinea pigs but should be considered as a differential diagnosis for abdominal masses.