December 2010

Case A

open slide in the AHA AAPSP Digital Slide Server


Bovine parotid lymph node submitted for exclusion of tuberculosis.

Example histopathological description

This image contains a section of lymph node, with attached adipose and connective tissue, and an unattached portion of a large blood vessel.  The lymph node architecture is defaced by a multi-lobulated, non-encapsulated mass that has caused compression and distortion of the residual lymphoid tissue.  The mass consists of anastamosing trabeculae of neoplastic squamous cells displaying considerable anaplasia, some dyskeratosis and a moderate mitotic index (1-2 per high power field).  In some areas of the mass there is extensive keratin pearl formation, and in others excessive keratin has coalesced to form lakes, often with mineralisation and early necrosis. There is mild to moderate reactive fibrosis within and at the margin of the mass in some areas.  However, neoplastic tissue extends to most margins of the section.  No lesion is evident in the unattached vessel.


Lymph node: metastatic squamous cell carcinoma.


There are no lesions suggestive of bovine tuberculosis in the section examined.

Case B

open slide in the AHA AAPSP Digital Slide Server


Neurological signs developed after temporary loss of water supply in a shed of weaner pigs.

Example histopathological description

This is a transverse section of one side of the cerebrum at the level of the basal ganglia.  It includes portion of the basal ganglia and all of the overlying cerebral cortex.  There is multifocally extensive laminar cerebrocortical necrosis with acute neuronal death, satellitosis, mild neuropil spongiosus, mild astrocytosis, prominent endothelial hypertrophy, congestion and oedema, which is more severe in some areas than in others.  Associated with severely affected areas there is mild to moderate perivascular cuffing with plasma cells, eosinophils and lymphocytes up to three cells deep.  In these areas the overlying leptomeninges are inflamed, showing similar perivascular infiltrates and oedema (which is severe in some areas).

Morphological diagnosis

Polioencephalomalacia (laminar cerebrocortical necrosis is equally acceptable); acute, diffuse, severe, with associated mild to moderate eosinophilic meningoencephalitis.

Aetiological diagnosis

Hypernatraemic polioencephalomalacia with eosinophilic meningoencephalitis (sodium intoxication or salt poisoning also acceptable).


A history of temporary loss of water supply and neurological signs associated with polioencephalomalacia and eosinophilic meningoencephalitis is highly diagnostic for induced hypernatraemia in pigs, and is generally all that is required for diagnosis.  However, additional confirmation can be achieved in the laboratory through serum, CSF or brain sodium assay.  Be aware that these concentrations are known to rapidly normalise following rehydration.