Cytologic features of oral squamous cell carcinoma in an Indo‐Pacific bottlenose dolphin (Tursiops aduncus): Papanicolaou stain and immunocytochemistry using liquid‐based cytology

Abstract

A captive male Indo-Pacific bot'tlenose dolphin (Tursiops aduncus) aged >45 years was reared in Okinawa Churaumi Aquarium (Japan). The animal had a history of a hemorrhagic ulcered mass (4 cm × 2 cm) on the right buccal mucosa that grew over a 2-year period (Figure 1) for which cytology and biopsy of the mass were performed to make a diagnosis.The oral lesion was scraped with a toothbrush to collect cells for the cytologic analysis, and the cells were immediately immersed and stirred in a large test tube containing 20 mL of CytoRich Red Preservative Fluid (Becton Dickinson). A liquid-based cytology (LBC) slide of the above sample was prepared using a modified SurePath method (Becton Dickinson) (Table 1; Figure 2). Three different SurePath slides were stained with Papanicolaou stain (Table 2), and p53 and p16 immunocytochemistry. For the p53 immunocytochemistry, antigen retrieval was performed with a citrate buffer (pH 6.0) heated at 90°C for 20 minutes. Then, a commercially available mouse, anti-human wild-type p53 protein antibody (clone DO-7,