Ferret Case

Age: 3Y


A 1 cm x 1 cm subq mass. Unknown how long mass present. Unable to obtain sample through FNA. Right doral neck.

Low magnification view of the lesion (as submitted), demonstrating overall architecture and a well demarcated mass.

Higher magnification view of the lesion (10X), demonstrating proliferative, elongated cells intersecting at 90 degree angles.

Click here for the IDEXX Pathology Report on this case.

Microscopic Description:

Haired skin: Arising from the arrector pili muscle, there is an infiltrative dermal mass comprised of sheets and bundles of neoplastic mesenchymal cells within a minimal fibrovascular stroma. Neoplastic mesenchymal cells are elongate with moderate eosinophilic cytoplasm. There is moderate anisocytosis and anisokaryosis. Nuclei are round to oval with lightly stippled chromatin and variably prominent small nucleoli. There are 0 mitotic figures identified per 10 400X fields. There are foci of necrosis.


Haired skin: Piloleiomyosarcoma

Mitotic Index:

0 (0 mitotic figures per 10 high power fields)


The lesion is separated from the closest lateral surgical margin by approximately 4.25 mm and the closest deep surgical margins by less than 1 mm in these particular sections.

Vascular Invasion:



Piloleiomyosarcomas are rare cutaneous neoplasms in ferrets. They have a unique histologic appearance and a characteristic immunohistochemical staining pattern. Despite the nuclear pleomorphism, the prognosis is presumably good following complete surgical excision.

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