Duncan Ann E, Smedley Rebecca, Anthony Simon, Garner Michael M
J Zoo Wildl Med. 2014 Sep;45(3):534-49. doi: 10.1638/2013-0207R1.1.
Malignant melanomas are aggressive neoplasms that are relatively common in penguins compared to other avian species. In this study, the clinical and pathologic characteristics of melanocytic neoplasms in five macaroni (Eudyptes chrysolophus), three rock hopper (Eudyptes chrysocome), and two Humboldt (Spheniscus humboldti) penguins are described. Tumors most commonly occurred in the skin of the foot or hock, and were seen in the subcutaneous muscle, especially near the beak/oral cavity. Gross lesions were usually heavily pigmented, becoming raised and ulcerated over time. Humboldt penguins had a unique presentation, forming variably pigmented, cornified lesions in the inguinal area. Original case materials were obtained from all but two cases, and were assessed to define the characteristics of malignancy, evaluate four immunohistochemical markers for melanoma, and look for factors useful to informing prognosis and clinical decisions. Diagnosis was made histologically, based on morphologic features and pigmentation. Though not necessary for diagnosis, PNL-2 was found to be a useful immunohistochemical marker. HMB-45 showed unreliable positive labelling and S-100, Melan-A and Ki67 were not useful. Several factors were associated with prognosis, including gross surface dimension, mitotic index, depth of neoplastic cell invasion, and degree of surface ulceration. Metastatic spread occurred to the liver, lung, adrenal gland, brain, and bone; all lesions showed positive labelling to PNL-2. The average survival after diagnosis was 7 mo, though complete surgical excision of tumors less than 2.0 cm was curative in two cases and radiation therapy prolonged survival in one penguin. The underlying pathogenesis associated with the high prevalence of melanocytic neoplasms in captive penguins could not be identified. Three different molecular methods were performed to look for viral particles and results were negative. Advanced age is the most probable associated risk factor; ultraviolet light and chlorine exposure, viral induction, and genetic predisposition were ruled out or considered unlikely.
恶性黑色素瘤是侵袭性肿瘤，与其他鸟类相比，在企鹅中相对常见。在本研究中，描述了5只通心粉企鹅（冠毛企鹅）、3只跳岩企鹅和2只洪堡企鹅中黑素细胞肿瘤的临床和病理特征。肿瘤最常发生在足部或跗关节皮肤，也见于皮下肌肉，尤其是靠近喙部/口腔处。大体病变通常色素沉着严重，随着时间推移会隆起并溃疡。洪堡企鹅有独特表现，在腹股沟区形成色素不一的角质化病变。除两例病例外，均获取了原始病例材料，并对其进行评估以确定恶性特征、评估四种黑色素瘤免疫组化标志物以及寻找有助于判断预后和临床决策的因素。根据形态学特征和色素沉着进行组织学诊断。虽然诊断并非必需，但发现PNL-2是一种有用的免疫组化标志物。HMB-45显示阳性标记不可靠，而S-100、Melan-A和Ki67无用。有几个因素与预后相关，包括大体表面尺寸、有丝分裂指数、肿瘤细胞浸润深度和表面溃疡程度。转移扩散至肝脏、肺、肾上腺、脑和骨；所有病变对PNL-2均呈阳性标记。诊断后的平均生存期为7个月，不过肿瘤小于2.0 cm的两例经完全手术切除治愈，一例企鹅经放疗后生存期延长。与圈养企鹅中黑素细胞肿瘤高发病率相关的潜在发病机制尚无法确定。采用三种不同分子方法寻找病毒颗粒，结果均为阴性。高龄是最可能的相关危险因素；排除或认为紫外线和氯暴露、病毒诱导及遗传易感性不太可能。
