Analysis of MDM2 and TP53 genes in canine liposarcoma.

Canine liposarcoma is an uncommon tumor that shares morphological similarities with its human counterpart. In dogs, the genetic features of this tumor are unknown and, based on immunohistochemical studies, amplification of the gene MDM2 and the mutation of TP53 are suspected. In this study 51 cases of primary liposarcomas were immunohistochemically stained for MDM2 and p53 and subjected to fluorescent in situ hybridization and next-generation sequencing to detect MDM2 amplification and TP53 mutations, respectively. MDM2 and p53 were expressed in 21 and 6 cases, respectively. MDM2 amplification and TP53 mutations were identified in 10 and 15 cases, respectively. Statistical analysis revealed an association of the myxoid subtype and the mitotic count with p53 expression and TP53 mutation. No association was found between MDM2 amplification and MDM2 expression or tumor subtype. These results suggest that despite morphological similarities, canine liposarcoma differs from its human counterpart, for which MDM2 amplification is diagnostic for well differentiated and de-differentiated variants, and TP53 mutations are more common in pleomorphic liposarcoma rather than the myxoid one as occur in our cases. Furthermore, canine myxoid liposarcoma likely represents a distinct disease rather than a mere morphological variant.

Hepatic Epithelioid Hemangioendothelioma in a Dog.

A 5-year-old spayed female Breton dog was referred for a thyroid nodule. A total body CT scan evidenced multifocal hepatic nodules. Cytological liver samples were hemodiluted and non-diagnostic. Following a thyroidectomy, the histology was consistent with a follicular-compact thyroid carcinoma. On laparoscopy, most hepatic lobes had multifocal dark-red nodules that were biopsied for histology. Microscopically, the hepatic parenchyma in the nodules was substituted by blood channels lined by bland spindle cells but adjacent to epithelioid neoplastic cells, single or in clusters, embedded in a moderate amount of edematous collagen matrix. These cells had optically empty cytoplasmic space, occasionally containing erythrocytes (microlumina). Spindle and epithelioid cells expressed membranous-to-cytoplasmic CD31 and FVIII-RA consistent with endothelial origin. Based on morphology and immunolabelling, a hemangioendothelioma with epithelioid differentiation was diagnosed. Lesions in the liver were initially stable, showing progression with time. The dog was alive with no systemic clinical signs 36 months after laparoscopy.

Identification of asinine gamma herpesviruses in a donkey with interstitial pulmonary fibrosis, pleural effusion and thrombocytopenia.

A 23-year-old domestic donkey (Equus asinus) referred for severe respiratory distress due to suspected equine asthma. Ultrasound of the chest revealed bilateral irregular pulmonary consolidation and pleural effusion. Airway endoscopy and tracheal wash cytology showed severe neutrophilic inflammation and bacterial culture was positive for Streptococcus equi subsp. zooepidemicus. Despite aggressive treatment, the donkey died in 48 hours. On post-mortem examination, the lung was whitish, collapsed, and firm, with fibrotic multifocal nodular areas. Pleural effusion and pleuritis were detected. Histologically, the lung architecture was markedly replaced by interstitial fibrosis. The histological features observed were suggestive of a severe chronic fibrosing interstitial pleuropneumonia with type 2 pneumocyte hyperplasia and intralesional syncytial cells. Pulmonary fibrosis was associated with the presence of asinine gammaherpesvirus 2 and 5 infection, confirmed by PCR and sequence analysis. The macroscopic and histological pattern of fibrosis was diffuse and interstitial, and the nodular lesions were consistent with spared lung parenchyma, instead of the canonical nodular distribution of the fibrosis observed in equine multinodular pulmonary fibrosis. Asinine herpesviral pulmonary fibrosis is uncommon, but should be considered by clinicians in the list of differentials in donkeys with chronic respiratory signs.