Oral squamous cell carcinoma in a pigtailed macaque (Macaca nemestrina).

An adult, gravid, female pigtailed macaque (Macaca nemestrina) presented for facial swelling centered on the left mandible that was approximately 5 cm wide. Differential diagnoses included infectious, inflammatory, and neoplastic origins. Definitive antemortem diagnosis was not possible, and the macaque's condition worsened despite supportive care. Necropsy findings included a mandibular mass that was locally invasive and expansile, encompassing approximately 80% of the left mandibular bone. The mass replaced portions of the soft palate, hard palate, sinuses, ear canal, and the caudal-rostral calvarium and masseter muscle. Histologically, the mass was a neoplasm that was poorly circumscribed, unencapsulated, and infiltrative invading regional bone and soft tissue. The mass consisted of polygonal squamous epithelial cells with intercellular bridging that breached the epithelial basement membrane and formed invasive nests, cords, and trabeculae. The mitotic rate averaged 3 per 400× field of view, with occasional bizarre mitotic figures. Epithelial cells often exhibited dyskeratosis, and the nests often contained compact lamellated keratin (keratin pearls). The neoplasm was positive via immunohistochemistry for pancytokeratin, variably positive for S100, and negative for vimentin, smooth muscle actin, and desmin. The gross, histologic, and immunohistochemical findings were consistent with an aggressive oral squamous cell carcinoma. The neoplasm was negative via PCR for papilloma virus. In general, neoplasia in macaques is rare. Although squamous cell carcinomas are one of the most common oral neoplasia in many species, to our knowledge this case represents the first reported oral squamous cell carcinoma in a pigtailed macaque.

一只成年怀孕的雌性豚尾猴（Macaca nemestrina）因左侧下颌骨为中心的面部肿胀前来就诊，肿胀宽度约5厘米。鉴别诊断包括感染性、炎症性和肿瘤性病因。生前无法明确诊断，尽管给予支持性治疗，豚尾猴的病情仍恶化。尸检结果显示下颌有一肿块，呈局部浸润性和膨胀性，累及约80%的左侧下颌骨。肿块取代了软腭、硬腭、鼻窦、耳道以及颅尾侧颅骨和咬肌的部分组织。组织学上，肿块为肿瘤，边界不清，无包膜，呈浸润性侵犯局部骨骼和软组织。肿块由多边形鳞状上皮细胞组成，细胞间有桥粒，突破上皮基底膜，形成浸润性巢状、索状和小梁状结构。在400×视野下平均有丝分裂率为3个/视野，偶尔可见奇异的有丝分裂象。上皮细胞常表现为角化不良，巢内常含有致密的板层状角蛋白（角蛋白珠）。通过免疫组化检测，肿瘤细胞角蛋白呈阳性，S100呈不同程度阳性，波形蛋白、平滑肌肌动蛋白和结蛋白呈阴性。大体、组织学和免疫组化结果符合侵袭性口腔鳞状细胞癌。通过聚合酶链反应检测，肿瘤乳头瘤病毒呈阴性。一般来说，猕猴的肿瘤很少见。虽然鳞状细胞癌是许多物种中最常见的口腔肿瘤之一，但据我们所知，此病例是首次报道的豚尾猴口腔鳞状细胞癌。