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Squamous cell carcinoma (SCC) is the most common neoplasm of the equine stomach. However, the mechanisms underlying malignant transformation are unknown. As Equus caballus papillomavirus–2 (EcPV-2) is a likely cause of some genital SCCs, we hypothesized that EcPV-2 is associated with a subset of equine gastric SCCs. To this aim, we performed polymerase chain reaction (PCR) and in situ hybridization (ISH) for EcPV-2 E6/ E7 oncogenes on 11 gastric SCCs and on gastric samples from 15 control horses with no SCC. PCR for EcPV-2 was positive in 7/11 (64%) gastric SCCs; non-SCC gastric samples were all negative. Intense hybridization signals for EcPV-2 E6/E7 nucleic acid were detected by ISH within tumor cells in 5/11 (45%) gastric SCCs, including distant metastases. No hybridization signals were detected within any of the non-SCC gastric cases. This study provides support for a potential association between EcPV-2 infection and a subset of equine gastric SCC.

Background: To describe the clinical presentation and treatment of an ectopic periorbital lymph node in two young horses. Case Description: Two Warm-Blood horses were presented at the equine clinic of the University of Liège with a periorbital non-painful mass. Differential diagnosis included neoplasm (lymphoma), (sterile) abscess, cyst, ectopic lacrimal gland tissue, hematoma, adipose tissue or ectopic lymphoid tissue. Information collected included physical and ophthalmic examination findings, results of ocular and periocular ultrasound, surgical procedure, histopathology and follow-up. Masses of 2x2cm and 3x2cm subcutaneous, ovoid, smooth, and firm mass were observed in the zygomatic region of the head. On ultrasound, the mass appeared as a hypoechoic subcutaneous structure. Cytology showed a mixed lymphocytic cell population. No abnormal mitotic activity was observed. Histopathology revealed a chronic markedly reactive lymph node. Conclusion: To the authors’ knowledge, this is the first description of periorbital ectopic lymph nodes in veterinary medicine. Ectopic lymph node should therefore be included in the differential diagnosis of periocular masses in animals. Surgery was easily performed and was curative.

An 11‐year‐old male neutered Boxer presented for evaluation of an external ear canal mass, postoperatively diagnosed as a benign inflammatory lesion. Preoperative staging of the ear mass identified a 10‐cm mass affecting the majority of the left lateral hepatic lobe, with inconclusive cytology. A left lateral liver lobectomy was performed. Histopathology revealed the hepatic parenchyma was largely effaced and replaced by a myriad of small calibre tubules lined by well‐differentiated biliary epithelium (cytokeratin19 and cytokeratin7 positive (CK19+, CK7+) supported by abundant fibrosis. Small cords and islands of hepatocytes (hepatocyte paraffin1 positive) (HepPar1+) were entrapped throughout these bile ducts. Analysis of the proliferation index via antigen KI‐67 (Ki67) immunohistochemistry confirmed lack of proliferative activity. Histological and immunohistochemical features were consistent with a ductal plate malformation (DPM). This is the first time a DPM of this size has been described on a computed tomography (CT) scan.

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