June 2006

Case A

AAPSP June 06 Rabbit mandible-Actino.jpg (114 KB)


Swelling on the mandible of a rabbit

Example histopathological description

This is a section of excised lesion. There is effacement of resident bone and connective tissue by multiple coalescing sheets of heterophilic inflammation with associated necrosis, surrounded by a narrow rim of macrophages and fibroblasts (abscesses). Within the abscesses are numerous bacterial colonies surrounded by homogeneous eosinophilic material (Splendore-Hoeppli material) often orientated as radiating club-shaped bodies about the bacterial colonies (club colonies). The fibrous connective tissue between the abscesses contains bone spicules and is infiltrated by small numbers of heterophils, lymphocytes, macrophages, giant cells and plasma cells.

Morphological diagnosis

Osteomyelitis, pyogranulomatous, chronic, multifocal, severe, with club colonies


When investigating club colonies the following table is a useful guide

Aetiology Gram stain characteristics Modified ZN
Actinomyces Positive filamentous bacilli negative
Nocardia Positive filamentous bacilli positive
Actinobacillus Negative coccobacilli  
Staphylococcus Positive cocci  

Case B

AAPSP June 06 Bovine liver-Fascioliasis.jpg (114 KB)


Abnormal bovine liver collected at an abattoir

Example histopathological description

This is a section of liver. There are several large, randomly distributed, foci of necrosis with replacement haemorrhage and infiltration by large numbers of eosinophils. Within one of these necrotic areas is a section of an immature trematode parasite characterized by an integument containing spines, anterior and ventral suckers, no coelomic cavity, absence of calcareous corpuscles and an alimentary tract that contains brown/black pigment. There is marked diffuse bile duct hyperplasia, portal and bridging fibrosis and portal infiltrates of eosinophils, lymphocytes and plasma cells. There is prominent hypertrophy of the wall of hepatic arterioles.

Morphological diagnosis

Cholangiohepatitis, fibrosing, chronic, diffuse, severe, with concurrent subacute, multifocal, severe, eosinophilic, necrotising hepatitis, with intralesional immature trematode

Aetiological diagnosis

Hepatic fascioliasis (acute and chronic)


Fasciola hepatica

Differential diagnosis

The differential diagnosis of trematodiasis in the bile ducts of cattle includes Dicrocoelium dendriticum(lancet fluke), Fasciola gigantica, Fasciola hepatica and Fascioloides magna. In addition, Eurytrema pancreaticum, whilst usually parasitising the pancreatic ducts, can also be found within bile ducts in severe infestations.

D dendriticum has no spines and E pancreaticum has a large anterior (oral) sucker whereas the one in the parasite in this section appears to be small. However, that may be due to plane of the cut of the section. F magna has a rounded posterior end, whereas the tail in this parasite appears to be tapered. F gigantica is morphologically similar to F hepatica but is much larger (25 – 75 mm. in length).

F hepatica is the only fluke in Australia known to infect cattle. It may reach a length of 30 mm, whereas the one in this section has an overall length of approximately 9 mm. The fact that the parasite is relatively small, its reproductive tract is not obvious and it is migrating through the liver parenchyma suggests it is still immature. To be absolutely certain of its identity, it and any other parasite present would need to be dissected out from the tissue and examined under a dissecting microscope.