Osteoblastoma-like osteosarcoma: high-grade or low-grade osteosarcoma?

AIMS: Osteoblastoma-like osteosarcoma is a rare variant of osteosarcoma (1% of all osteosarcomas), histologically similar to osteoblastoma. In the current World Health Organisation (WHO) classification, osteoblastoma-like osteosarcoma is classified within the group of conventional (high-grade) osteosarcomas. However, several published cases have been actually regarded as low-grade malignant tumours. As strict morphological criteria to distinguish between low- and high-grade lesions are not available, we reviewed our series of osteoblastoma-like osteosarcomas in the attempt to identify clinical and morphological features predictive of aggressiveness. METHODS AND RESULTS: We retrieved 15 cases of osteoblastoma-like osteosarcoma from the files of the Istituto Ortopedico Rizzoli. Patients received various treatments. Five patients developed metastasis and five patients developed local recurrences (all after incomplete surgery). Eleven patients were alive without disease, while four patients died of their disease. Statistical analysis revealed a statistically significant (P = 0.048) lower disease-free survival in patients with areas of conventional (high-grade) osteosarcoma. CONCLUSIONS: With the important limitation of a small cohort of patients, the presence of areas of conventional (high-grade) osteosarcoma is the only parameter to predict the aggressiveness of osteoblastoma-like osteosarcoma.

Surgical management of spinal osteoblastomas.

OBJECTIVE Osteoblastoma is a rare primary benign bone tumor with a predilection for the spinal column. Although of benign origin, osteoblastomas tend to behave more aggressively clinically than other benign tumors. Because of the low incidence of osteoblastomas, evidence-based treatment guidelines and high-quality research are lacking, which has resulted in inconsistent treatment. The goal of this study was to determine whether application of the Enneking classification in the management of spinal osteoblastomas influences local recurrence and survival time. METHODS A multicenter database of patients who underwent surgical intervention for spinal osteoblastoma was developed by the AOSpine Knowledge Forum Tumor. Patient data pertaining to demographics, diagnosis, treatment, cross-sectional survival, and local recurrence were collected. Patients in 2 cohorts, based on the Enneking classification of the tumor (Enneking appropriate [EA] and Enneking inappropriate [EI]), were analyzed. If the final pathology margin matched the Enneking-recommended surgical margin, the tumor was classified as EA; if not, it was classified as EI. RESULTS A total of 102 patients diagnosed with a spinal osteoblastoma were identified between November 1991 and June 2012. Twenty-nine patients were omitted from the analysis because of short follow-up time, incomplete survival data, or invalid staging, which left 73 patients for the final analysis. Thirteen (18%) patients suffered a local recurrence, and 6 (8%) patients died during the study period. Local recurrence was strongly associated with mortality (relative risk 9.2; p = 0.008). When adjusted for Enneking appropriateness, this result was not altered significantly. No significant differences were found between the EA and EI groups in regard to local recurrence and mortality. CONCLUSIONS In this evaluation of the largest multicenter cohort of spinal osteoblastomas, local recurrence was found to be strongly associated with mortality. Application of the Enneking classification as a treatment guide for preventing local recurrence was not validated.

Management Strategy of Osteoblastomas Localized in the Occipitocervical Junction.

OBJECTIVE: The aim of this article was to analyze extracted patient data from the literature and highlight the best treatment options and survival outcomes for osteoblastomas in the occipitocervical region. METHODS: A systematic literature search method was used to select articles containing information about the demographic features, tumor location, treatment characteristics, adjuvant therapies, and follow-up time. RESULTS: From 25 articles, 31 cases of osteoblastoma in the occipitocervical junction were selected for analysis. Average patient age was 17 years (range, 5-57 years); there were 21 male (67%) and 10 female (33%) patients. All patients had cervical pain as the presenting symptom. Other symptoms included torticollis (0.13%) and sensory or motor neurologic deficits (0.16%). The average follow-up time was 41 months, and the local recurrence rate was 0.125%. Recommendations of each article are categorized and discussed in detail. CONCLUSIONS: Osteoblastoma is a rare entity in the occipitocervical region, so treatment experiences are limited and mostly based on case reports. To determine the best treatment for these lesions, osteoblastomas should be staged using the Enneking staging system; different methods may be recommended for different stages, and the feasibility of fusion depends on the remaining amount of bony structures and joints. Additional adjuvant therapies may be recommended only in special cases.

Staging and treatment of osteoblastoma in the mobile spine: a review of 51 cases.

PURPOSE: To define the role of Enneking staging system and of the consequent different treatment options on the outcome of osteoblastoma (OBL) of the spine. METHODS: A retrospective review of 51 patients with OBL of the mobile spine conducted to compare the outcomes among the different types of treatments at long term follow-up (25-229 months, av.90). These 51 patients were previously staged according to Enneking staging system and treatment selected accordingly. 10 stage two (st.2) OBLs were treated with intralesional excision and 41 stage three (st.3) OBLs were treated either by intralesional excision or en bloc resection. The intralesional excision group was divided considering the use or not of radiation therapy after surgery. The recurrence rate was compared among these groups and also considering previous open surgery ("non intact" vs. "intact"). The statistical significance was defined using the Fisher Exact test. RESULTS: No local recurrence occurred in the st.2 patients treated by intralesional excision. Considering the st.3 patients, 2 local recurrences out of 13 patients occurred in the en bloc resection (15.4 %) group. All occurred in "non intact" cases (67 %). In the intralesional group, 5 local recurrences out of 27 patients occurred (18 %) being none in the group that received radiation therapy after surgery. Two occurred in the "intact" (7 %) and three in the "non intact" group (75 %). Considering all patients, the difference between the recurrence rate between "intact" and "non intact" groups was statistically significant (p < 0.002). CONCLUSIONS: Intralesional excision proved to be effective in st.2 lesions and en bloc resection in st.3. Radiotherapy seems to be an effective adjuvant treatment when en bloc resection is not feasible or requires unacceptable functional sacrifices. The first treatment significantly affects the prognosis as previously treated patients have worse prognosis.