Chordoma in a Ferret
History: mass on the tail that had been there several months with sudden changes in size.
The subcutis contains a well demarcated, unencapsulated, moderately cellular neoplasm composed of sheets of large vacuolated round cells (physaliferous cells) mixed with islands of cartilage and bone. Neoplastic cells have abundant cytoplasm containing variably sized clear vacuoles and distinct cell borders. The nuclei are oval with finely granular cytoplasm and 1-3 nucleoli. There are 2 mitotic figures in 10 400x fields. The neoplasm is completely excised.
Chordomas are very common, typically benign, neoplasms of ferrets. They are thought to arise from the remnant of the notochord from the developing embryo. In ferrets they are usually found in the tail and efface one or more caudal vertebrae, presumably because the intertebral disc is also a remnant of the developing notochord. Chordomas are characterized by central zones of bone or cartilage surrounded by vacuolated, balloon-like “physaliferous cells” in a myxoid stroma. The degree of organization is variable.