December 2014
Case A
History
Tissue from a four month old dog housed in an animal shelter. Clinically, there was a mild cough and upper respiratory tract signs which became more severe over a seven day period.
Example Histopathological Description
Both sections of lung are partly consolidated by extensive fibrinous intra-alveolar effusion and variably dense accumulations of leucocytes. These are predominantly neutrophils which are densest, degenerate and partly inspissated where they appear to be spilling from bronchioles whose epithelium has mostly disappeared. In surviving epithelium of a few bronchioles, and in occasional alveolar-lining cells, there are large basophilic intranuclear inclusion bodies associated with margination of nuclear chromatin. While there are extensive areas of necrosis and haemorrhage, there are also zones where there is collapse and alveolar walls are thickened by incipient fibrosis.
Morphological Diagnosis
Bronchopneumonia; fibrino-suppurative and necrotising, severe, subacute, multifocal.
Bronchiolitis, multifocal, subacute, moderate, with intranuclear inclusion bodies.
Aetiological Diagnosis
Canine adenovirus-2 pneumonia, with secondary bacterial infection.
December 2014
Case B
History
Tissue from a neutered, male, adult domestic shorthaired cat with weight loss, renal insufficiency and pulmonary infiltrate. Irregular raised lesions were present on the ventral surface of the tongue.
Example Histopathological Description
One side of this cross-section of tongue shows extensive ulceration of ventral and lateral surfaces; the associated surviving mucosa is either spongiotic or hyperplastic. Most of the ventral submucosa is greatly thickened by a bulky infiltrate of neutrophils fairly uniformly mixed with large mononuclear histiocytic-type cells with large, mostly ovoid, nuclei with bland chromatin patterns, and abundant uniform cytoplasm which rarely contains small (approximately 2 μm diameter) faintly basophilic bodies, usually within a clear space. Immunocytes are not common, but there are scattered occasional foci of lymphocytes and plasma cells. This infiltrate extends into and between bundles of adjacent lingual muscle. Fibrosis is minimal.
Morphological Diagnosis
Glossitis; pyogranulomatous, ulcerative, focally extensive, chronic.
Aetiological Diagnosis
Chronic mycotic glossitis due to Histoplasma capsulatum.
Comments
Other deep mycoses (e.g. sporotrichosis, cryptococcosis); atypical mycobacterial infection; eosinophilic granuloma complex; and uraemic glossitis should be considered in the differential diagnosis. Special stains (PAS, GMS, modified ZN) would help confirm the diagnosis. Immunohistochemistry could be used if suitable antibodies are available, and/or fresh tissue submission for culture in the event of local recurrence.
Histoplasmosis has been reported in Australia (Mackie JT, Kaufman L, Ellis D. Confirmed histoplasmosis in an Australian dog. Aust Vet J 1997 75: 362-363)