September 2006

Case A

AAPSP September 06 Canine skin-Demidecosis.jpg (98 KB)


Mature dog with crusty skin lesions along the dorsum.

Notes on histopathological description

A description of ‘intrafollicular organisms consistent with mites’ is probably satisfactory for this common disease.  However, a brief description of the distinguishing anatomical features is recommended as a general practice when parasites are present in tissue sections.

Morphological Diagnosis

Folliculitis and furunculosis, pyogranulomatous, chronic, diffuse, severe, with intralesional arthropod parasites and coccoid bacteria

Aetiological Diagnosis

Generalised pustular demodicosis.  In this case the severity of furunculosis warrants designation as the pustular form of generalised demodicosis.


This is a common disease with few differentials. However, characterisation of the coccoid bacteria using a gram stain is recommended. Recovery of parasites for specialist microscopy is required for definitive identification.

Case B

AAPSP September 06 Bovine brain-Pompes disease.jpg (89 KB)


Neurological signs were apparent in a nine-month-old Angus bull.

Notes on histopathological description

This is a section of the medulla oblongata approximately at the level of the obex. The key features are vacuolar distension of neuronal perikarya, axonal spheroid formation and vacuolation of vascular myocytes. Gliosis is equivocal.

Morphological diagnosis

Encephalopathy, vacuolar, neuronal, chronic, diffuse, severe

Aetiological diagnosis

Lysosomal storage disease, probably generalised glycogenosis type II.


The preferred diagnosis is lysosomal storage disease, most probably generalised glycogenosis type II. The differential diagnosis should include other known genetically transferred lysosomal storage diseases (e.g. mannosidosis) and toxic diseases (e.g. swainsonine-induced mannosidosis). A novel lysosomal storage disease can not be completely excluded. Special stains for glycogen are recommended to distinguish glycogenosis from mannosidosis. Genetic testing may be needed for confirmation of glycogenosis.