An adult bronze-winged parrot (Pionus chalcopterus) was presented for post-mortem examination following death without antecedent clinical signs. Macroscopically, the liver was expanded by a 14×12×10mm, off-white to grey, infiltrative mass with 3-8mm diameter nodular masses on the serosa of the duodenum. Cytology of impression smears of the hepatic mass revealed a monomorphic population of epithelial cells, arranged in cohesive clusters, occasionally with an acinar-like arrangement. Histologically, the neoplasm was unencapsulated, infiltrative, well-demarcated and moderately densely cellular. Neoplastic cells were arranged in well-defined, variably sized acini and tubules that were supported by a fine collagenous stroma. Acini and tubules frequently contained intraluminal eosinophilic proteinaceous material. Neoplastic cells were small to moderately sized and were generally columnar or cuboidal with well-delineated cell boundaries and a small amount of eosinophilic to basophilic cytoplasm. The nuclei were round, frequently basally located and had densely stippled chromatin and usually a single, prominent, magenta nucleolus. There were two mitoses in 10 high-power fields (2.37mm2). Vascular invasion was observed and metastatic nodules of similar neoplastic cells were present on the duodenal serosa. Immunohistochemical labelling for cytokeratin 19 revealed weak to moderate, punctate cytoplasmic expression in <10% of neoplastic cells. Macroscopically, cytologically and histologically the neoplasm was consistent with a cholangiocarcinoma.

An increased incidence of bacterial pneumonia (BP) has been reported in Irish Wolfhounds (IWHs) and the disease typically recurs repeatedly. The aetiology is unclear but the development of bronchiectasis in the absence of clinical findings indicative of interstitial lung disease is common in affected IWHs. This observation led us to hypothesize that the primary cause could be at bronchial level. We evaluated bronchial cartilage structure and composition in IWHs (n=10) with previous episodes of pneumonia compared with IWH control dogs (n=5) and other large-breed control dogs (n=5) without a history of respiratory disease. Histological evaluation of lung sections was performed with haematoxylin and eosin, Masson's trichrome and Prussian blue staining as well as with immunohistochemistry (IHC) for CD3 and CD79a antigens and pancytokeratin. Bronchial cartilage proteoglycan content was evaluated in sections stained with safranin 'O' (SO) and chondrocyte apoptosis by IHC for cleaved caspase-3. Image analysis was used to measure the bronchial cartilage to lumen area ratio as well as the SO staining intensity and caspase-3-positive cell count in digital whole slide images. The most consistent histological finding in the lungs of IWHs with recurrent BP was chronic lymphoplasmacytic inflammation in the peribronchial and perivascular pulmonary interstitium, along with remodelling of the bronchial walls. The bronchial cartilage to lumen area ratio was significantly lower in all IWHs than in control dogs of other breeds (P=0.011), suggesting less cartilage support in the bronchi of the IWH breed. The SO staining intensity of the bronchial cartilage was significantly higher (P=0.008) in affected IWHs than in control dogs of other breeds. Analysis of caspase-3 immunolabelling of large bronchial cartilage revealed significantly fewer apoptotic chondrocytes in affected IWHs than in all control dogs (P=0.045). Based on these findings, altered cartilage metabolism, as a breed-related feature or secondary to chronic inflammation, may play a role in the pathogenesis of bronchiectasis development and recurrent lung infections in IWHs.

Myofibroblastic fibrosarcoma (MFS) is a malignant soft tissue tumour that is rare in domestic animals. Here we report a case of congenital MFS in an Arabian foal at birth. A large solitary subcutaneous mass arising in the left temporal region was found in the foal. On cut section, an unencapsulated hemispheric, white-yellowish, elastic fibrous mass was attached to the temporal bone. Histologically, the mass was composed of a neoplastic proliferation of spindle-shaped fibroblasts arranged in fasciculate or interwoven streams and bundles, with low nuclear atypia and mitotic rate, local invasion of the surrounding soft tissues and temporal bone, non-metastasis and abundant collagenous stroma. Immunohistochemically, vimentin, calponin, desmin and alpha-smooth muscle actin were strongly and diffusely labelled, S100 was mildly labelled and h-caldesmon was weakly labelled in the cytoplasm of the neoplastic cells; however, the neoplastic cells were immunonegative for pancytokeratin AE1/AE3 and p63. Based on the histological and immunohistochemical findings, a diagnosis of MFS was made. To our knowledge, this is the first report of congenital MFS in animals.