Case A
open slide in the AHA AAPSP Digital Slide Server
History
A 14-month-old steer with a clinical history of ventral dermatitis. Lesions form conical crusts of matted hair that, when pulled away, leave pink, moist, exudative skin.
Example histopathological description
This is a section of haired skin. The epidermis has moderate, irregular acanthosis and basal hyperplasia along with marked orthokeratotic and parakeratotic hyperkeratosis. The cornified layer has a laminated appearance with embedded layers of degenerate inflammatory cells and proteinaceous debris. Throughout the stratum corneum are numerous scattered mites and occasional eggs. The mites are oval, typically dorsoventrally flattened with a striated chitinous exoskeleton, jointed appendages, striated muscle, a hemocoelom, a digestive tract and a reproductive tract. The eggs are oval with an anisotropic shell. There is mild to moderate acanthosis and hyperplasia of the infundibular epithelium of hair follicles, which often contain accumulations of granulocytes. Within the outer root sheath of hair follicles and scattered throughout the superficial crusts are filamentous organisms with apparent transverse and longitudinal septation. The dermis contains a moderate cellular infiltrate composed predominantly of plasma cells with fewer lymphocytes and granulocytes.
Morphological diagnosis
Dermatitis, perivascular, hyperplastic and superficial, chronic, diffuse, severe, with hyperkeratosis, folliculitis, intracorneal mites and filamentous bacteria
Aetiological diagnosis
This was a case of Chorioptes bovis infestation together with dermatophilosis (Dermatophilus congolensis) in the skin.
Case B
open slide in the AHA AAPSP Digital Slide Server
History
A five-month-old Abyssinian female cat died overnight in a cattery. This cat and others had a history of upper respiratory tract infection over the last week.
Example histopathological description
This is a section of lung lobe apex bounded on two sides by pleura. There is an extensive region of consolidation and haemorrhage involving approximately one half of the lung parenchyma. In this region, tertiary bronchi and bronchioles exhibit complete necrosis and sloughing of the mucosal epithelium with disruption of the mucosal musculature, abundant intraluminal and submucosal necrotic cell debris, and marked neutrophil and moderate macrophage infiltration. Alveoli are filled with erythrocytes, fibrin, proteinaceous fluid, neutrophils and alveolar macrophages. Alveolar septa are moderately thickened by a similar exudate, and exhibit type 2 pneumocyte hypertrophy, or are acutely necrotic. There is perivascular oedema and infiltration with inflammatory cells. In the remainder of the section, changes to alveoli and bronchioles are similar in nature but less severe, and patchy alveolar emphysema is evident. Particularly appreciable in bronchioles with intact mucosal lining in these less severely affected regions, and also involving pneumocytes, are abundant intraepithelial, eosinophilic to amphophilic, large intranuclear inclusions that marginate chromatin.
Morphological diagnosis
Pneumonia, bronchointerstitial, fibrinonecrotising and suppurative, acute, multifocal, severe, with intralesional intranuclear inclusion bodies.
Aetiological diagnosis:
This was a case of feline herpesvirus pneumonia, confirmed by PCR on fresh lung tissue.