Parosteal Osteosarcoma: A Benign-Looking Tumour, Amenable to a Variety of Surgical Reconstruction.

Osteosarcoma arising from cortical surface is classified into parosteal, periosteal and high-grade surface osteosarcoma. Along the spectrum, parosteal osteosarcoma occupies the well-differentiated end. It is a relatively rare disease entity, comprised only 4% of all osteosarcomas and barely reported in the literature. The objective of this study is to describe cases of parosteal osteosarcoma as well as a variety of treatment options amenable to such entity. Six cases of parosteal osteosarcoma were identified based on histopathological reports in a tertiary referral hospital in Jakarta, Indonesia between January 2001 and December 2019. The mean age was 29.8 years old; four of them (66.7%) were male. Distal end of femur was the most commonly involved bone (five cases, 83.3%). The patients were treated with wide excision followed by several different reconstruction methods: replacement with endoprosthesis, extracorporeal irradiation, knee arthrodesis, or prophylactic fixation. One of our patients presented with dedifferentiated component, and therefore was treated by limb ablation. While two cases died of pulmonary metastasis, other patients reported fair to excellent functional outcome.

Parosteal osteosarcoma: a monocentric retrospective analysis of 195 patients.

Parosteal osteosarcoma is a low-grade malignant bone tumor that can undergo dedifferentiation. The aim of this study was to analyze clinicopathologic features associated with clinical outcome in a large cohort of patients. Patients consecutively treated for parosteal osteosarcoma at Rizzoli Orthopedic Institute from 1900 to 2018 were reviewed and analyzed. Clincopathologic data of 195 patients with parosteal osteosarcoma were analyzed. Age at diagnosis ranged from 9 to 75 years (median 31). Median follow-up time was 150 months (range, 3-720). The most common tumor locations were femur (61.5%), humerus (15.9%) and tibia (12.8%). Wide surgical margins were achieved in 125 (64.1%) patients. Medullary involvement was present in 69 (35.4%) cases. Dedifferentiation occurred in 48 (24.6%) patients. Forty-five patients developed recurrence (23.1%; median time to recurrence of 36 months). At last follow-up, 155 (79.5%) patients were alive and without evidence of disease, 8 (4.1%) were alive with active disease, 23 (11.8%) died from disease, and 9 (4.6%) from unrelated causes. Patients with dedifferentiated parosteal osteosarcoma had worse 5-year (65% versus 96%) and 10-year survival (60% versus 96%) when compared to conventional tumors (P < .001). Wide surgical margins had positive impact on both disease-free (P < .001) and overall survival (P = .036). Medullary involvement, age at presentation and tumor size had no impact on survival. Dedifferentiation is the most important factor that negatively impacts clinical outcome. Surgical aim is to ensure radical removal with wide surgical margins to improve disease-free survival.

A comparison of intramedullary and juxtacortical low-grade osteogenic sarcoma.

UNLABELLED: While low-grade juxtacortical and low-grade intramedullary osteogenic sarcomas are histologically indistinguishable, they have been studied as separate entities. We retrospectively reviewed the clinical, radiographic, histologic features and treatment of 59 patients treated surgically to compare the rate of local recurrence, grade progression, and survival between low-grade intramedullary and low-grade juxtacortical osteogenic sarcoma. Forty-five (76%) patients were treated for low-grade juxtacortical osteogenic sarcoma and 14 (24%) were treated for low-grade intramedullary osteogenic sarcoma. Local recurrence rates of 7% were similar for both groups studied. The rate of distant metastases was also similar for both groups. . The rate of dedifferentiation for the entire group was 29%. Dedifferentiated lesions were treated with adjuvant chemotherapy in 16 of 17 cases. Recurrence preceded dedifferentiation in four cases. Five-year survival was over 90% in both groups. Low-grade intramedullary and low-grade juxtacortical osteogenic sarcoma were clinically indistinguishable with identical rates of local recurrence, distant metastases, dedifferentiation, and survival. LEVEL OF EVIDENCE: Level III, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Conventional and dedifferentiated parosteal osteosarcoma. Diagnosis, treatment, and outcome.

BACKGROUND: Dedifferentiated parosteal osteosarcoma (dd-POS) designates high grade transformation, of conventional low grade parosteal osteosarcoma (c-POS). The paradigm of preoperative diagnosis, neoadjuvant chemotherapy, and wide local excision has not been adequately evaluated for dd-POS, as it has been for conventional high grade intramedullary osteosarcoma. METHODS: A retrospective review was conducted of 28 patients treated at the authors' institution between January 1980 and December 1992 for an osteosarcoma arising on the surface of the bone diagnosed as either c-POS or dd-POS. The clinicopathologic features, diagnosis, treatment, and patient outcome were analyzed. RESULTS: A dedifferentiated component was identified in 12 of 28 tumors (43%). Neither the presence of radiolucencies (77% in c-POS and 100% in dd-POS, P = 0.06) nor medullary invasion (42% in c-POS and 50% in dd-POS, P = 0.28) distinguished dd-POS from c-POS. However, all patients who presented with focal hypervascularity on an arteriogram defined the high grade component of dd-POS that was confirmed by selective needle biopsy. This differed significantly (P = 0.00003) from c-POS. None of the patients with c-POS died of the disease (median survival duration, 77 months; range, 16-152 months). Six patients (35%) developed a local recurrence, but five were treated successfully with further surgery. In the dd-POS group, 7 of the 12 patients died of the disease. Ten patients with dd-POS received preoperative chemotherapy (IA cis-diamminedichloroplatinum, IV doxorubicin), and a good response (> 90% necrosis of high grade component) was observed in four. Among patients whose disease was localized, continuous disease free survival was prolonged significantly (P = 0.03) in patients with a good response (median, 75 months) compared with those who responded poorly (median, 13 months). Five patients remained continuously disease free (median, 66 months, range, 29-95 months). CONCLUSIONS: Wide surgical excision alone is adequate treatment for patients with c-POS. Recognition of dedifferentiated areas with angiography and percutaneous biopsy of hypervascular areas should prompt the administration of chemotherapy and wide local excision to optimize patient outcome.

Limb salvage in primary malignant bone tumors by intraoperative microwave heat treatment.

OBJECTIVE: To use intraoperative microwave heat for the treatment of tumor-bearing bone in situ for limb-salvage in primary malignant bone tumor. PATIENTS AND METHODS: Twenty-five patients with malignant bone tumor received surgical protocol for limb-salvage by wide exposure and intraoperative microwave heat treatment of tumor bone in situ. The tumor was localized at distal femur in 16 patients, proximal tibia in 5, shaft of femur in 2, and illia in 2. RESULTS: The pathological diagnosis revealed osteosarcoma in 16 patients, parosteal osteosarcoma in 4, chondrosarcoma in 3, and leiomyosarcoma in 2. The stage of tumor was classified into IIB in 16 patients, IIA in 6, and IIIB in 3. The operative technique was wide exposure for tumor in soft tissues, protecting the surrounding normal tissue from heat injury by copper mesh, and heating tumor-bearing bone at 50 degrees C for 15 minutes. The patients were followed up from 4 to 180 months (mean, 63 months). The survival rate of 2, 5 and 10 years was 81.3%, 70.4%, and 53.8% respectively. The functional results were less than 50% in 4 patients, between 50% and 75% in 9, and more than 75% in 12, referred to the normal function of a normal limb. The complications consisted of infection in 4 patients, pathological fracture in 4, and separation of epiphysis in 1. Oncological results showed that local recurrences of tumor were in 4 patients, and 6 patients suffered from distant metastasis. CONCLUSION: The treatment is an alternative to replacement by prosthesis or allograft bridging techniques.

Parosteal osteosarcoma. A clinicopathological study.

The records of 226 patients (sixty-seven who were managed at our institution and 159 who were identified from the consultation files) who had had a parosteal osteosarcoma were reviewed. The criteria for diagnosis were that, roentgenographically, the lesion had arisen from the surface of the bone and that, histologically, the tumor was well differentiated (Grade 1 or 2); it was characterized by well formed osteoid within a spindle-cell stroma; and, when there was medullary involvement, less than 25 per cent of the medullary cavity was affected. Dedifferentiation was more common (16 per cent of the patients) than previously reported and was associated with a poor prognosis. Cross-sectional imaging studies demonstrated medullary involvement in 22 per cent of the patients, an unmineralized soft-tissue mass peripheral to the mineral component in 51 per cent, and adjacent soft-tissue invasion in 46 per cent. In contrast to the findings in our previous studies, medullary involvement was not a poor prognostic factor. At an average of thirteen years (range, two to forty-one years), eleven of the sixty-seven patients who were managed at our institution died of the tumor; ten of these patients had a dedifferentiated tumor. Statistical analysis of the thirty-nine patients who had had the primary treatment at our institution revealed that incomplete resection was associated with an increased risk of local recurrence and that dedifferentiation markedly increased the risk of metastasis.