September 2013

Case A

Proficiency testing Case study A – AAPSP Slide server


This was the second rabbit to show respiratory distress and die in a group of 100 Large New Zealand White rabbits.

Example Histopathological Description

This section of lung contains multiple lobules with pleura and/or interlobular septae on three sides. There is marked inflammation with consolidation of pulmonary parenchyma affecting 90% of the tissue present. There is focally extensive necrosis of alveoli with intense infiltrates of heterophils, macrophages and erythrocytes. In less severely affected areas the alveoli are flooded with protein-rich oedema fluid, heterophils and macrophages, with occasional colonies of bacteria (possibly coccobacilli).  In the peripheral zone of most lobules there is type II pneumocyte hyperplasia, apparent syncytia formation, some early interstitial fibrosis and mild lymphocyte accumulations. Bronchial lumens are expanded by desquamated epithelial cells, erythrocytes and heterophils and there are moderate peribronchial lymphocytic infiltrates. Some foci of degenerate heterophils are discrete, signifying early abscess formation.  Interlobular septae are severely expanded by fibrinosuppurative inflammation and there is marked heterophilic vasculitis.  The pleura is diffusely and markedly expanded with heterophils, erythrocytes, oedema fluid, fibrin and bacterial colonies.

Morphological Diagnosis:

Pneumonia; fibrinosuppurative, subacute, diffuse, severe, with intralesional bacteria.

Pneumonia; interstitial, subacute to chronic, multifocal, severe, with type II pneumocyte hyperplasia and early fibrosis.

Pleuritis; fibrinosuppurative, subacute, diffuse, severe, with intralesional bacteria.

Aetiological Diagnosis:

Bacterial pleuropneumonia consistent with pasteurellosis.


Case B

Proficiency testing Case study B – AAPSP Slide server

Koala; 11-years-old, found disoriented and depressed. Euthanased.

Example Histopathological Description

This is a para-sagittal section of the cerebellum and underlying medulla oblongata. Diffusely distributed in the white matter of the cerebellum, are dozens of discrete vacuoles which are circular to ovoid in shape and up to 100 µm in diameter.  These vacuoles are mostly empty but some contain an occasional naked axon or thin strand of myelin.  Throughout the cerebellar white matter, not necessarily associated with the vacuoles, there is mild hypertrophy and hyperplasia of glial cells, involving both astrocytes and oligodendrocytes.  Similar vacuoles are occasionally present in the brainstem but here there is no evidence of gliosis.  There are handling and/or fixation artefacts in several areas, especially in some cerebellar folia and some parts of the brain stem.

Morphological Diagnosis

Cerebellum: leucoencephalopathy; spongiform, diffuse, moderate, subacute, with mild gliosis.

Brain stem: leucoencephalopathy, spongiform, diffuse, mild, subacute.


Likely causes include:

  • Renal and/or hepatic encephalopathy
  • Severe metabolic abnormalities secondary to stress
  • Toxic agents – phytotoxins, mycotoxins, pharmacologic agents
  • Prion disease or other idiopathic spongiform encephalopathy