Honey's autopsy pictures
Yet another DIY post mortem...
Lump on spleen
Gas filled stomach
Abdomen lymph node
Left gooey kidney
Left gooey kidney
Right kidney and left gooey kidney
Honey's histopathlogy report
Post-Mortem Tissues from a Ferret: 12 samples received; 12 sections evaluated on 4 slides.
Heart (slide 1). This sagittal wedge section of the myocardium and great vessels shows no lesions.
Lung (slide 3). There is extensive atelectasis. Alveolar capillaries often appear congested. Many venules in the parenchyma are cuffed by up to 15 cell layers of uniform small to medium-sized lymphocytes, with 1 to 3 mitotic figures per individual high-power (400x) field. There are no other remarkable findings.
Adipose Tissue (slide 3). There is patchy congestion. Multifocally, adipocytes and stromal venules show smudged cellular detail (artefact of barbiturate euthanasia, or if not applicable, then early autolysis). There are no other remarkable findings.
Spleen (slide 1). There is moderate generalized congestion. The red pulp contains scattered clusters of mixed haematopoietic precursor cells. Lymphoid sheaths and follicles are regularly distributed with normal cellularity but are small. There are no other remarkable findings.
Lymph Nodes or Thymus (6 sections, slides 4 and 5). Some of these sections show hints of recognizable nodal architecture (outlines of medullary cords and sinuses), and no recognizable thymic architecture can be seen. Otherwise, all architectural detail is replaced and effaced by a sheet of monomorphic small to medium-sized lymphocytes. The lymphocytes also colonize stroma and extend beyond a thin collagenous capsule into adjacent adipose tissue. There are on average 6 mitotic figures per individual high-power field. There are no other remarkable findings.
Kidney (2 sections, slide 2). One of these wedge sections is largely occupied by an expansile, unilocular cyst, approximately 12 mm in diameter, that extends from the subcapsular cortex through to the deep cortex. The cyst replaces and displaces renal elements. The cyst is lined by a single layer of cuboidal to markedly attenuated cells, supported by a delicate rim of collagen. The lumen of the cyst is partly filled by eosinophilic (proteinaceous) fluid. The renal stroma and parenchyma immediately adjacent to the cyst sometimes appear normal and sometimes show extensive patchy areas of sclerosis of all elements associated with a moderately dense infiltrate of small to medium-sized lymphocytes with fewer plasma cells and macrophages. In a few foci, the lymphocytes seem to form a monomorphic sheet and these lymphocytes occasionally contain mitotic figures. The other wedge section shows a very slightly irregular renal capsular contour, associated with occasional wedges of stromal fibrosis accompanied by a light infiltrate of lymphocytes and plasma cells. Glomeruli sometimes show dilated capillary loops with luminal fibrinous thrombi. Occasional glomeruli are sclerotic. Rarely, renal tubules and medullary ducts contain small mineral concretions. There are no other remarkable findings.
1. Lymph Nodes (possibly also Thymus, per history): Lymphoma, small cell but high-grade
2. Lung: Lymphoma, perivascular, small cell
3. Kidney: Lymphoma, small cell, unilateral, focal
4. Kidney: Renal Cyst
5. Kidney: Interstitial Nephritis and Glomerulonephritis -- multifocal, chronic, mild
As you had correctly suspected, this ferret had malignant lymphoma. One mass, presumably the mediastinal mass mentioned on the history form, appears to be a lymph node that has been overrun by lymphoma, but it remains possible that both a lymph node and thymus tissue are present -- the tumour has nearly effaced all identifying features of the tissue. Lymphoma is the most common malignancy of the domestic ferret. It most frequently arises spontaneously, although there is increasing circumstantial evidence of a transmissible form. This particular lymphoma does not fit neatly into any of the three categories most commonly seen in ferrets (low-grade small cell in mature ferrets, high-grade immunoblastic without nodal involvement in young ferrets, or immunoblastic-polymorphous form), but of course, a wide variety of lymphoma types can occur in any species. Lymphoma in ferrets often involves the viscera, and in this case there is infiltration by the tumour into the lung and probably into one kidney. In one recent study, mean survival time for all ferrets with lymphoma was only 5.6 months (Reference: Ammersbach M, Delay J, Caswell JL, Smith DA, Taylor WM, Bienzle D. Laboratory findings, histopathology, and immunophenotype of lymphoma in domestic ferrets. Vet Pathol. 2008 Sep; 45(5): 663 - 73.). This malignancy would account for the bulk of this ferret's clinical signs.
As an incidental finding, one of this ferret's kidneys shows a non-neoplastic renal cyst. Renal cysts are common in the ferret, and some authors state that they are found incidentally in about one third of animals at post-mortem examination. Their origin is uncertain, though in the absence of severe chronic renal disease which might have caused acquired cysts, they are probably developmental lesions. They are generally of little clinical significance and have no effect on renal function. Some such cysts may attain a large size, but owing to the tough nature of the renal capsule, they almost never rupture. In rare cases in ferrets, there is true polycystic renal disease, which may cause renal failure -- polycystic kidneys are composed of variable numbers of cysts with little intervening fibrous connective tissue. As only a single cyst is seen here and as no other cysts are reported on the submission form, polycystic disease appears unlikely in this case.
Finally, the kidneys also show mild chronic interstitial nephritis and glomerulonephritis, neither seeming severe enough to have caused the renal cyst. These are common lesions in mature carnivores. Although there would have been potential for progression, ultimately resulting in compromised renal function, these renal lesions do not appear severe enough to have had much clinical importance at this stage.