A Pediatric Case of Metastatic Conventional Parosteal Osteosarcoma Treated With Multidrug Chemotherapy.

Parosteal osteosarcoma (POS) is conventionally a low-grade sarcoma with limited metastatic potential; however, the tumor occasionally transforms into a high-grade dedifferentiated POS, which commonly metastasizes to distant organs. The present report describes a rare pediatric case of conventional POS with no dedifferentiated component yet had multiple pulmonary metastases at initial diagnosis. Following limb-sparing surgery and osteosarcoma-oriented neoadjuvant chemotherapy, the patient received total resection of pulmonary metastases. Despite no treatment for pulmonary recurrence 1 year after adjuvant chemotherapy, the patient is alive with stable disease 4 years and 6 months after the initial diagnosis.

[Parosteal osteosarcomas: unusual findings]. / Osteosarcomas parostales: resultados infrecuentes.

OBJECTIVE: To study and evaluate the unusual findings in the natural history of parosteal osteosarcomas. Parosteal osteosarcomas are well-differentiated tumours of low grade malignancy, but may dedifferentiate into a more aggressive lesion. MATERIAL AND METHODS: We reviewed 7 parosteal osteosarcomas treated in La Paz Hospital between 2005 and 2009 (3 were dedifferentiated parosteal osteosarcomas). The authors analysed the clinical and radiological features, histology, treatment and outcomes in this patient group. RESULTS: There were 5 men and 2 women, with a mean age of 32.14 years, range 24-47 years. Three of seven tumours (42.8%) were dedifferentiated osteosarcomas. All three patients received chemotherapy. One patient presented with pulmonary metastases. No patient died. CONCLUSIONS: It is important to understand that the biological phenomenon of dedifferentiation can occur in parosteal osteosarcomas. The prognosis, treatment and survival changes radically.

Telomerase activity in juxtacortical and conventional high-grade osteosarcomas: correlation with grade, proliferative activity and clinical response to chemotherapy.

Seven samples from seven patients with juxtacortical osteosarcomas, and 27 samples from 19 patients with conventional high-grade osteosarcomas were investigated for a possible correlation between telomerase activity and clinicopathological features such as age, sex, and response to chemotherapy. Of seven juxtacortical osteosarcomas, telomerase activity was weakly positive in three parosteal osteosarcomas, and highly positive in one parosteal osteosarcoma. In contrast, of 27 conventional high-grade osteosarcomas, telomerase activity was weakly positive in eight tumors and highly positive in three. Of all samples, 44.1% of the osteosarcomas showed telomerase activity (57.1% of juxtacortical and 40.7% of conventional osteosarcomas). The majority of poor responders to chemotherapy showed no telomerase activity (nine of 11), whereas five of seven good responders showed strong or weak telomerase activity. There was a significant correlation between telomerase activity and the response to chemotherapy (P<0.05). Telomerase activity was not correlated with MIB-1 proliferation index, age at the time of surgery, or sex. These findings suggest that telomerase activation occurs early in the oncogenesis of osteoblastic tumors without having an effect on the progression of these tumors. In malignant osteoblastic tumors, the biological significance of telomerase activation is different from that described for most epithelial cancers.

Telangiectatic dedifferentiation of a parosteal osteosarcoma.

A unique case of parosteal osteosarcoma (POS) of the proximal femur, with areas of telangiectatic dedifferentiation, in a 28-year-old woman is reported. The patient had a 7-week history of pain and swelling in her right thigh. A biopsy diagnosis of POS was established. The patient was treated with two cycles of intraarterial chemotherapy, followed by limb salvage surgery. Histological examination of the resected specimen showed POS with areas of dedifferentiation composed of highgrade telangiectatic osteosarcoma with associated secondary aneurysmal bone cyst change.

Tumores ósseos malignos na criança e no adolescente / Malignant bone tumors in children and adolescent

Os tumores malignos primários dos ossos representam cerca de 10 porcento das neoplasias que acometem crianças e adolescentes. Os tumores de Ewing e o osteossarcoma säo os mais frequentes (95 porcento) nas duas primeiras décadas de vida. Enorme evoluçäo nas taxas de cura ocorreu nos últimos anos, graça a novos recursos da cirurgia e da moderna quimioterapia. A sobrevida livre de doença em cinco anos pode hoje ser conseguida, para ambas as doenças, em cerca de 60 pocento a 70 porcento dos casos. As cirurgias de conservaçäo do membro - endopróteses ou enxertos ósseos - podem oferecer condiçöes de manutençäo de funçäo adequada de membros, em lugar de amputaçöes, atualmente reservadas para tumores mais avançados. Para que estes objetivos possam ser alcançados, descrevemos neste artigo informaçöes para o diagnóstico precoce e a sequência terapêutica recomendada