Proliferative lesions of the spleen are common in ferrets. diffuse enlargement and dark reddening is usually due to extramedullary hematopoiesis. Occasionally, lymphoma is a diffuse process, but more often is multinodular and tan to white. Hematoma is also occasionally seen. The pictured lesion is a hemangiosarcoma in the spleen, which is relatively rare in ferrets. Photo courtesy Northwest ZooPath.