Can Osteoblastoma Evolve to Malignancy? A Challenge in the Decision-Making Process of a Benign Spine Tumor

The Role of En Bloc Resection in the Modern Era for Primary Spine Tumors

STUDY DESIGN

A literature review.

OBJECTIVE

The aim of this review is to provide an overview of benign and malignant primary spine tumors and a balanced analysis of the benefits and limitations of (and alternatives to) surgical treatment with en bloc resection.

SUMMARY OF BACKGROUND DATA

Primary spine tumors are rare but have the potential to cause severe morbidity, either from the disease itself or as a result of treatment. The prognosis, goals, and treatment options vary significantly with the specific disease entity. Appropriate initial management is critical; inappropriate surgery before definitive treatment can lead to recurrence and may render the patient incurable, as salvage options are often inferior.

METHODS

We performed a comprehensive search of the PubMed database for articles relevant to primary spine neoplasms and en bloc spine surgery. Institutional review board approval was not needed.

RESULTS

Although Enneking-appropriate en bloc surgery can be highly morbid, it often provides the greatest chance for local control and/or patient survival. However, there is growing data to support modern radiotherapy as a feasible and less morbid approach to certain primary neoplasms that historically were considered radioresistant.

CONCLUSIONS

Choosing the optimal approach to primary spine tumors is complex. A comprehensive and up-to-date assessment of the evidence is required to guide patient care and to balance the often-competing goals of prolonging life and preserving quality of life.

Multimodal Imaging Evaluation and Clinical Progress of Spinal Osteoblastoma: A Comprehensive Review

Spinal osteoblastoma is rare clinically, with insidious onset, atypical symptoms, and various imaging manifestations, which can easily lead to misdiagnosis and delayed diagnosis. It can cause severe neurological dysfunction in patients with intermediate to advanced stages and may easily recur after surgery. Imaging examinations such as radiography, computed tomography, magnetic resonance imaging, and positron emission tomography have different value for the diagnosis of spinal osteoblastoma, but they lack specificity. The preferred treatment is surgical resection, which is technically difficult, and in some cases, osteoblastoma cannot be completely removed. New clinical approaches such as radiofrequency ablation, radiotherapy, targeted chemotherapy, and other comprehensive treatments have emerged and are progressing rapidly, but no unified norms have yet been developed. This manuscript provides a systematic review of the literature and provides an extensive and comprehensive review of this rare tumor in terms of multimodality imaging manifestations and clinical progress.

Outcomes of Surgical Treatment for Extradural Benign Primary Spinal Tumors in Patients Younger than 25 Years: An Ambispective International Multicenter Study

Extradural primary spinal tumors were retrospectively analyzed from a prospective database of 1495 cases. All subjects with benign primary tumors under the age of 25 years, who were enrolled between 1990 and 2012 (Median FU was 2.4 years), were identified. Patient- and case-related characteristics were collected and statistically analyzed. Results: 161 patients (66f;95m; age 17.0 ± 4.7 years at time of diagnosis) were identified. The most common tumors were osteoblastomas n = 53 (32.9%), osteoid osteomas n = 45 (28.0%), and aneurysmal bone cysts n = 32 (19.9%). The tumor grade, according to the Enneking Classification S1/S2/S3, was 14/73/74 (8.7/45.3/46.0%), respectively. Tumor-related pain was present in 156 (96.9%) patients. Diagnosis was achieved by biopsies in 2/3 of the cases. Spinal fixation was used in >50% of the cases. Resection was Enneking appropriate in n = 100 (62.1%) of cases. Local recurrence occurred in 21 (13.1%) patients. Two patients died within a 10-year follow-up period. Conclusion: This is one of the largest international multicenter cohorts of young patients surgically treated for benign spinal tumors. The heterogenic young patient cohort presented at a mid-term follow-up without a correlation between the grade of aggressiveness in resection and local recurrence rates. Further prospective data are required to identify prognostic factors that determine oncological and functional outcomes for young patients suffering from these rare tumors.

Surgical treatment scenario for osteoblastoma of the pelvis: Long-term follow-up results

BACKGROUND

The aim of this study was to evaluate the results of different treatments for pelvic Osteoblastoma (OB).

METHODS

We retrospectively evaluated 34 patients affected by primary pelvic OB from 3 oncologic referral centers. Patients with a minimum follow-up of 24 months were included. Local recurrence (LR) rate and complications were recorded.

RESULTS

The primary treatment was radio-frequency ablation (RFA) in 4 patients (11.8%), curettage (ILC) in 21 (61.7%) and resection (EBR) in 9 (26.5%). Mean follow-up was 8.9 years (SD ± 6.6). Local recurrence free survival (LRFS) rate after primary surgery was 79.4% at 3 and 5 years. In details, LRFS rate at 3 and 5 years was 50.0% in RFA, 81.0% in ILC and 88.9% in EBR. Post-operative complications occurred in 6/34 patients (17.7%), in particular after EBR.

CONCLUSIONS

RFA is the least invasive technique to treat OB but with high LR rate. Thus, it should be reserved to very small lesions. ILC is a suitable treatment for stage II OB. For stage III OB, EBR is the treatment of choice, despite an increased risk of complications. For selected stage III OB (relatively small, periacetabular area) ILC might be considered.

Epithelioid osteoblastoma. Clinicopathologic and immunohistochemical study of 17 cases

Seventeen cases of epithelioid osteoblastoma were reviewed. The tumors most commonly arose from the vertebrae (7 cases), followed by the mandible (3), sacrum (2), bones of the foot (2), and femur, rib, and scapula (1 each). Patients' ages ranged from 5 to 33 years. The tumors measured from 2.0 to 6.5 cm in the greatest diameter (mean = 4.1 cm) and most patients presented with low-grade pain at the affected site. Imaging studies showed expansile lytic lesions with cortical thickening and a mild rim of sclerosis. Histologically all tumors were characterized by active production of bone with a fibrovascular stroma containing microtrabecular aggregates of bone matrix. The osteoblastic proliferation was atypical and showed enlarged cells with prominent nucleoli and abundant cytoplasm imparting them with a striking epithelioid appearance. Immunohistochemical studies showed variable results that caused difficulties for interpretation; 4 of 12 cases showed strong nuclear positivity for FOS, 2 of 12 cases showed strong diffuse nuclear positivity for FOSB; the remaining cases showed variable, sometimes overlapping patterns, considered to be indeterminate. Ki-67 proliferation marker showed low nuclear positivity (∼2%) in 10 cases and a slight increase (<10%) in two cases. Clinical follow-up was available in 14 patients; one patient experienced a recurrence at six months that was treated with additional curetting; the remainder of the patients were all alive and well without evidence of recurrence from 1 to 22 years (median follow up = 3 years). Epithelioid osteoblastoma is an unusual variant of osteoblastoma that has the potential for simulating a malignancy and does not appear to be associated with a more aggressive behavior.

Management of Osteoblastoma and Giant Osteoid Osteoma with Percutaneous Thermoablation Techniques

Osteoblastoma (OB) is a rare, benign bone tumor, accounting for 1% of all primary bone tumors, which occurs usually in childhood and adolescence. OB is histologically and clinically similar to osteoid osteoma (OO), but it differs in size. It is biologically more aggressive and can infiltrate extraskeletal tissues. Therapy is required because of severe bone pain worsening at night. Moreover, non-steroid anti-inflammatory drugs (NSAIDs) are not a reasonable long-term treatment option in young patients. Surgical excision, considered the gold standard in the past, is no longer attractive today due to its invasiveness and the difficulty in performing a complete resection. The treatment of choice is currently represented by percutaneous thermoablation techniques. Among these, Radiofrequency ablation (RFA) is considered the gold standard treatment, even when the lesions are located in the spine. RFA is a widely available technique that has shown high efficacy and low complication rates in many studies. Other percutaneous thermoablation techniques have been used for the treatment of OB, including Cryoablation (CA) and laser-ablation (LA) with high success rates and low complications. Nevertheless, their role is limited, and further studies are necessary.

Osteoblastoma: When the Treatment Is Not Minimally Invasive, an Overview

Background: osteoblastoma is a bone-forming tumor accounting for about 1% of all primary bone tumors and 3% of benign bone tumors. The gold-standard treatment is surgical excision; nevertheless, minimally invasive radiological techniques such as thermoablation and, more recently, high intensity focused ultrasound are gaining more importance. The aim of the present paper is to analyze surgical indications based on our experience and on the evidences in the literature. Methods: all patients affected by osteoblastoma who underwent surgical excision in January 2009 and December 2018 were reviewed; eleven patients were enrolled in the study. The epidemiological aspects, size of the disease and site of onset, symptoms, surgery type, indications, and results are reported for every case. Results: all treatments were based on a preoperative diagnosis; pain was constant in all cases. Intralesional surgeries were performed in 9 out of 11 cases; the remaining 2 cases underwent wide resection. No early or late complications occurred after the surgical procedure. The indications for surgery were lesions very close to nerves or joints, unclear diagnosis, risk of fracture, lesion too large for radiofrequency thermoablation, or failure of minimally invasive treatments. At a medium follow-up of 88 months, no local recurrences were verified. Conclusions: osteoblastoma is a rare tumor with difficult diagnosis. Identification is based on symptoms, imaging, and histology. When possible, minimally invasive techniques is preferred for treatment but surgery is still considered the gold standard.

Osseous Tumor Reporting and Data System-Multireader Validation Study

OBJECTIVE

To develop and validate an Osseous Tumor Reporting and Data System (OT-RADS) with the hypothesis that the proposed guideline is reliable and assists in separating benign from malignant osseous tumors with a good area under the curve, and that could assist further patient management.

METHODS

In this multireader cross-sectional validation study, an agreement was reached for OT-RADS categories based on previously described magnetic resonance imaging features and consensus of expert musculoskeletal radiologists. World Health Organization classification was used, and a wide spectrum of benign and malignant osseous tumors was evaluated. Magnetic resonance imaging categories were as follows: OT-RADS 0-incomplete imaging; OT-RADS I-negative; OT-RADS II-definitely benign; OT-RADS III-probably benign; OT-RADS IV-suspicious for malignancy or indeterminate; OT-RADS V-highly suggestive of malignancy; and OT-RADS VI-known biopsy-proven malignancy or recurrent malignancy in the tumor bed. Four blinded readers categorized each tumor according to OT-RADS classification. Intraclass correlation (ICC) and Conger κ were used. Diagnostic performance measures including area under the receiver operating curve were reported. Osseous Tumor Reporting and Data System was dichotomized as benign (I-III) and malignant (IV and V) for calculating sensitivity and specificity.

RESULTS

Interreader agreement for OT-RADS (ICC = 0.78) and binary distinction of benign versus malignant (κ = 0.67) were good to excellent, while agreement for individual tumor feature characteristics were poor to fair (ICC = 0.25-0.36; κ = 0.16-0.39). The sensitivities, specificities, and area under the receiver operating curve of the readers ranged from 0.93-1.0, 0.71-0.86, and 0.92-0.97, respectively.

CONCLUSIONS

Osseous Tumor Reporting and Data System lexicon is reliable and helps stratify tumors into benign and malignant categories. It can be practically used by radiologists to guide patient management, improve multidisciplinary communications, and potentially impact outcomes.