Fibroblastic osteosarcoma in a white-eared opossum (Didelphis albiventris) / Osteossarcoma fibroblástico em gambá-de-orelha-branca (Didelphis albiventris)

Osteosarcoma is characterized by the production of osteoid or woven bone, using neoplastic osteoblasts. It is the most common primary bone neoplasm in canines and humans. This neoplasm was previously reported in all vertebrate classes, including a wide variety of mammals. However, there is no case report describing this neoplasm in Didelphis albiventris. Therefore, the objective of this manuscript is to describe the clinical-pathological aspects of fibroblastic osteosarcoma in D. albiventris. A wild adult male white-eared opossum (D. albiventris) arrived at the zoological park of the "Universidade de Caxias do Sul" with a swollen left thoracic limb. After a general clinical examination, the animal was transferred to the Veterinary Clinic of "Universidade de Caxias do Sul" for radiographic examination of the left thoracic limb and thorax. Additionally, some material was collected through fine needle aspiration (FNA) for cytologic evaluation. The radiographic findings and cytologic evaluation indicated osteosarcoma. The animal was euthanized due to severe clinical conditions and guarded prognosis. During necropsy, macroscopic analysis of the viscera was performed, fragments of various organs were collected and fixed in 10% neutral buffered formalin. All fragments were processed following routine histological techniques. The histopathological evaluation confirmed osteosarcoma, which was classified as a fibroblastic subtype. Case reports are crucial for the knowledge of incidence, prevalence, and behavior of the current mentioned disease, as well as other diseases, in species with such limited information. In order to obtain a decisive diagnosis, a few different examination methods were associated. Although the observations presented are based on a single case, this neoplasm had a similar clinical presentation to that described in other species.(AU)

O osteossarcoma é caracterizado pela produção de osteoide ou osso imaturo, por osteoblastos neoplásicos. É a neoplasia óssea primária mais comum em caninos e humanos. Essa neoplasia já foi relatada em todas as classes de vertebrados, incluindo uma grande variedade de mamíferos. Não havendo descrição dessa neoplasia até o momento em Didelphis albiventris. O objetivo deste trabalho é descrever aspectos clínico-patológicos de um caso de osteossarcoma fibroblástico em D. albiventris. Chegou para atendimento no Zoológico da Universidade de Caxias do Sul um gambá-de-orelha-branca (D. albiventris), macho, adulto, de vida livre com aumento de volume no membro torácico esquerdo. Após avaliação clínica geral, o animal foi encaminhado para a Clínica Veterinária da Universidade de Caxias do Sul para realização de radiografia do membro torácico esquerdo e de tórax, sendo também realizada coleta de material por punção aspirativa por agulha fina (PAAF) para avaliação citológica. Os achados radiográficos e da avaliação citológica foram sugestivos de osteossarcoma. Devido ao estado clínico grave e prognóstico reservado optou-se pela eutanásia. Durante a necropsia realizou-se a análise macroscópica das vísceras, foram coletados fragmentos de diversos órgãos, fixados em formalina 10%, processados pelas técnicas histológicas de rotina. Na avaliação histopatológica confirmou-se a suspeita de osteossarcoma sendo classificado no subtipo fibroblástico. A descrição de relatos é fundamental para conhecimento da incidência, prevalência e comportamento desta e de outras doenças em espécies que as informações são limitadas. A associação de diferentes métodos de exames foram necessários para a obtenção de um diagnóstico definitivo. Embora as observações apresentadas se baseiem em um caso único, esta neoplasia possuiu apresentação clínica semelhante a descrita em outras espécies.(AU)

Epiphyseal osteosarcoma revisited: four illustrative cases with unusual histopathology and literature review.

Osteosarcomas arising in the epiphysis are extremely rare and easily missed in the diagnostic consideration of epiphyseal tumors. It is the purpose of this study to delineate the clinical pathological characteristics of 'epiphyseal osteosarcoma' under the definition of 'a solitary long bone osteosarcoma radiographically considered an epiphyseal tumor for which the main radiologic differential diagnosis would encompass giant cell tumor, chondroblastoma and clear cell chondrosarcoma'. Four such cases with unusual histopathology were retrieved among 110 cases of osteosarcoma. Their clinical, radiological and pathological features, together with all 10 reported cases, were analyzed. The radiographic diagnoses of our four cases include two giant cell tumors, one chondroblastoma and one clear cell chondrosarcoma but turn out to be fibroblastic, giant cell rich, telangiectatic and epithelioid variant of epiphyseal osteosarcoma. Including our patients, the 14 reported epiphyseal osteosarcomas comprise 8 males and 6 females, the age at presentation ranges from 11 to 39 years, two-third in the second decade, 71.4% affect the femur. Due to their epiphyseal locations, many carry benign radiological diagnoses notably giant cell tumor and chondroblastoma. Epiphyseal osteosarcomas may not only masquerade as benign radiological bony lesions but also assume many histological patterns; orthopedic surgeons, radiologists and pathologists should be aware of such possibility. Their behavior and prognosis are dictated by the histologic types, grading and staging rather than location.

Osteosarcoma of jaws.

Tumors of jaw bones are among the most uncommon of all types of neoplasms. Osteosarcoma of jaw bones represents a distinct group of lesions from the conventional type commonly occurring in long bones. Nonetheless, our present knowledge of the tumor allows us to affirm that its clinical behavior and pathologic features differ markedly from those of its homolog in the long bones. The maxillary tumors show predilection for posterior portion of the alveolar process and the antrum, whereas the body is most commonly involved in the mandible followed, by angle, symphysis, and ascending ramus. We have reviewed around 300 cases of osteosarcoma of varied racial origin from PubMed indexed journals spanning from 1967 to 2010 and present their etiology, pathogenesis, features and treatment modalities.