Osteoblastoma of the thumb with a novel PRSS44::ALK fusion and literature review of osteoblastoma of hands and feet bones.

Osteoblastomas (OBs) are benign neoplasms constituting approximately 1% of primary bone tumors with a predilection for the spine and sacrum. We describe an OB of the proximal phalanx of the left thumb in a 38-year-old female. MRI of left hand demonstrated a 29-mm mildly expansile enhancing lesion involving the entire proximal phalanx of the first digit. Histology displayed a bone-forming tumor consisting of trabeculae of remodeled woven bone framed by plump osteoblasts in a vascularized background. Next-generation sequencing analysis identified a PRSS44::ALK fusion gene.

Neonatal osteoblastic tumor with a novel PTBP1::FOSB fusion.

Congenital/neonatal bone neoplasms are extremely rare. We present the case of a patient with a neonatal bone tumor of the fibula that had osteoblastic differentiation and a novel PTBP1::FOSB fusion. FOSB fusions are described in several different tumor types, including osteoid osteoma and osteoblastoma; however, these tumors typically present in the second or third decade of life, with case reports as young as 4 months of age. Our case expands the spectrum of congenital/neonatal bone lesions. The initial radiologic, histologic, and molecular findings supported the decision for close clinical follow-up rather than more aggressive intervention. Since the time of diagnosis, this tumor has undergone radiologic regression without treatment.

Benign Brain and Spinal Tumors Originating from Bone or Cartilage.

Benign osseocartilaginous tumors of the spine are overall uncommon, representing between 1 and 13% of all primary bone tumors and less than 10% of all spinal tumors. Tumors in this category include osteoblastic lesions such as the related osteoid osteoma and osteoblastoma, and cartilage-forming lesions including osteochondroma, chondroma, and chondroblastoma. Aneurysmal bone cysts, giant cell tumors of bone, and eosinophilic granulomas also comprise benign tumors of the spine arising from bone. There is significant heterogeneity in the epidemiology, molecular biology, imaging features, and optimal treatment of these lesions. For example, osteoid osteoma is characterized by high expression of the cyclooxygenase enzymes, making it amenable to treatment with anti-inflammatory drugs initially, whereas other lesions such as osteoblastoma may require intralesional curettage or en bloc resection sooner. Generally, en bloc resection is preferred when possible to minimize risk of recurrence. Further, some tumors may arise in the setting of syndromic conditions, such as multiple chondromas arising in Ollier disease or Maffucci syndrome, or as part of genetic disorders, such as osteochondromas in the context of hereditary multiple exostosis. These lesions may present with local pain, cause neurological compromise or be discovered incidentally on routine imaging. The Enneking classification and Weinstein-Boriani-Biagini system are routinely used to classify lesions and assist in surgical planning. More novel techniques such as radiofrequency ablation and laser photocoagulation have been applied for the treatment of osteoid osteoma and may have utility in the treatment of other lesion types. A multidisciplinary approach is critical in the management of benign lesions of the spine, and both chemotherapeutic and surgical approaches are routinely used.

Musculoskeletal oncology and thermal ablation: the current and emerging role of interventional radiology.

The role of interventional radiology (IR) is expanding. With new techniques being developed and tested, this radiology subspecialty is taking a step forward in different clinical scenarios, especially in oncology. Musculoskeletal tumoral diseases would definitely benefit from a low-invasive approach that could reduce mortality and morbidity in particular. Thermal ablation through IR has already become important in the palliation and consolidation of bone metastases, oligometastatic disease, local recurrences, and treating specific benign tumors, with a more tailored approach, considering the characteristics of every patient. As image-guided ablation techniques lower their invasiveness and increase their efficacy while the collateral effects and complications decrease, they become more relevant and need to be considered in patient care pathways and clinical management, to improve outcomes. We present a literature review of the different percutaneous and non-invasive image-guided thermal ablation methods that are currently available and that could in the future become relevant to manage musculoskeletal oncologic diseases.

The malignant transformation of osteoid osteoma in the cervical spine to high-grade osteosarcoma: a case report and review of literature.

PURPOSE: Osteoid osteoma occasionally occur in the spine, but their malignant transformation is not common. We present an extremely rare case of the malignant transformation of an osteoid osteoma to high-grade osteosarcoma that formed in the pedicle and spread to the lateral mass of the cervical spine. CASE PRESENTATION: We report the case of an 18-year-old man who suffered from neck pain as an initial symptom. The size of the radiolucent lesion was 12 mm in diameter at the time of diagnosis. Intralesional tumour resection and autologous bone grafting were performed. The remaining tumour grew gradually for 40 months after the surgery; therefore, the tumour had grown rapidly till 51 months after the initial diagnosis. At this stage, the tumour size was approximately 6-fold larger than the initial size, and resulted in progressive paraplegia. A biopsy revealed that the tumour had transformed into a high-grade osteosarcoma. Heavy charged particle irradiation was performed to control tumour growth. CONCLUSIONS: There is a possibility of malignant transformation of osteoid osteoma. Patients with osteoid osteoma or osteoblastoma should be carefully observed, especially for recurrent tumours after an intralesional resection.

Epithelioid osteoblastoma with secondary aneurysmal bone cyst and FOS gene rearrangement.

Epithelioid osteoblastoma, sometimes equated with aggressive osteoblastoma, is a variant of osteoblastoma that typically demonstrates more worrisome imaging and pathological features compared to conventional osteoblastoma. These more aggressive features can overlap with those seen in osteosarcoma, creating a diagnostic challenge for radiologists and pathologists. Recent identification of FOS and FOSB gene rearrangements in osteoid osteoma and osteoblastoma has allowed for greater diagnostic confidence following biopsy, but careful radiological-pathological correlation remains a key component for guiding appropriate management. Although the imaging features of conventional osteoblastoma have been previously described, there are limited examples in the literature of the imaging appearance of epithelioid osteoblastoma, and none with secondary aneurysmal bone cyst. In this case report, we detail the clinical, imaging, and histological characteristics of a proximal femoral epithelioid osteoblastoma which was pathologically confirmed by FOS and FOSB genetic testing. The initial imaging impression favored a malignancy, but when the biopsy results were correlated in a multidisciplinary fashion with the imaging, epithelioid osteoblastoma became the leading diagnosis which was subsequently genetically confirmed. This case emphasizes the value of multidisciplinary radiology-pathology correlation in routine practice.

Osteoblastoma of the Distal Radius.

Osteoblastomas are rare, benign, bone-forming neoplasms that represent less than 1% of all bone tumors and occur mostly in people aged 10 to 30 years. In long bones, the metadiaphyseal region tends to be most commonly affected. However, to the best of our knowledge, only 11 cases have been reported to occur in the distal radius. We present the clinical, radiological, and histopathological findings of an osteoblastoma of the right distal radius in a 42-year-old woman for whom an open excisional biopsy with nidus removal comprised the treatment and produced a good outcome.

[Giant cell-containing tumors of bone and differential diagnoses]. / Riesenzell-haltige Tumoren des Knochens und Differenzialdiagnosen.

Osteoclastic giant cells represent a common cellular component of lesions arising in bone. Highlighting this morphological finding, the current WHO classification of bone tumors defines a diagnostic group comprising aneurysmal bone cyst, giant cell tumor of bone and non-ossifying fibroma, which may display morphologic similarities while being distinct with regard to molecular and biological features. Starting with these tumors - putting a focus on lesions arising in bone - this article gives a survey of other (chondrogenic and osteogenic) tumors that frequently contain osteoclastic giant cells, which may, particularly in small biopsies, enter differential diagnosis. Overlapping features with selected giant cell-containing soft tissue tumors, which may be of differential diagnostic relevance in daily routine, are discussed.

Paediatric fronto-orbital osteoblastoma: case report.

Osteoblastoma is a rare benign bone tumour. It represents 1% of all primary bone tumours. Common locations are the vertebral column and long bones of the extremities. Although well documented in craniofacial locations, only occasional case reports describe orbital involvement. The authors present a case of a fronto-orbital osteoblastoma which posed a significant diagnostic dilemma. Despite early local recurrence, the molecular findings were supportive of a benign lesion.

Minimally Invasive Resection of Benign Osseous Tumors of the Spinal Column: 10 Years' Experience and Long-Term Outcomes of a Specialized Center.

Background and Objectives: Benign osseous tumors of the spinal column comprise about 10% of all spinal tumors and are rare cause for surgery. However, these tumors pose various management challenges and conventional surgery may be associated with significant morbidity. Previous reports on minimally invasive resection of these lesions are rare. We report a series of patients managed by total resection of benign osseous spine tumors using MIS techniques. Surgical decisions and technical considerations are discussed. Materials and Methods: A retrospective evaluation of prospectively collected data of patients who underwent minimally invasive surgery for removal of benign osseous vertebral tumors. Demographic, clinical and radiographic features, operative details and final pathological reports were summarized. Primary outcomes were completeness of tumor resection and pain relief assessed by VAS for back and leg pain. Secondary outcome measures were recurrence of tumor on repeat post-operative MRI and postoperative unstable deformity on standing scoliosis X-rays. Results: This series included 32 cases of primary osseous spine tumors resected by minimally invasive techniques. There were 17 males and 15 females aged 5-68 years (mean 23.3). The follow-up period was 8-90 months (mean 32 months) and the preoperative symptoms duration was 9-96 months. Axial spinal pain was the presenting symptom in all the patients. Five patients also complained about radicular pain and four patients had antalgic scoliosis. The tumor involved the thoracic spine in 12 cases, the lumbar segment in 11, the cervical in 5 and the sacral area in 4 cases. Complete tumor removal was performed in all patients. No procedure-related complications were encountered. Histopathology showed osteoid osteoma in 24 patients, osteoblastoma in 5 patients, and fibrous dysplasia, fibroadenoma and eosinophilic granuloma in one case each. All patients experienced significant pain relief after surgery, and had stopped pain medications by 12 months postoperatively. No patient suffered from tumor recurrence or spinal deformity. Conclusions: Minimally invasive surgery is feasible for total removal of selected benign vertebral tumors and may have some advantages over conventional surgical techniques.

Significant Improvement After Surgery for a Symptomatic Osteoblastoma in a Patient with Camurati-Engelmann Disease: Case Report and Literature Review.

Camurati-Engelmann disease (CED) is a rare, progressive diaphyseal dysplasia characterized as diaphyseal hyperostosis and sclerosis of the long bones. Corticosteroids, bisphosphonates, and losartan have been reported to be effective systemic medications used to reduce CED symptoms. There are no reports of osteoblastoma in patients with CED, and osteoblastoma in the distal radius is rare. We present a patient diagnosed with CED, based on radiological and histological examinations, at 11 years old. At 22 years old, she experienced severe pain in her right forearm and was treated with bisphosphonate, losartan, and prednisolone; however, the pain continued. An expansive and sclerotic lesion at the distal radius was observed on radiography. A follow-up plain radiograph indicated that the lesion was growing. Fluorodeoxyglucose positron emission tomography revealed solitary, intense radiotracer uptake, and a biopsy and surgical resection were performed due to suspected malignancy. Pathologic analysis showed anastomosing bony trabeculae rimmed by osteoblasts observed in a loose fibrovascular stroma. The lesion was diagnosed as an osteoblastoma. Following bone excision and artificial bone grafting, the patient's severe pain almost completely disappeared. At final follow-up, no evidence of osteoblastoma recurrence was noted. To our knowledge, this is the first case report of osteoblastoma arising in a patient with CED. Bone excision and artificial bone grafting may be a treatment option for local symptomatic osteoblastoma in patients with CED.

Osteoblastoma of the mandible in a male patient: a case report.

Osteoblastoma is a rare benign osteoblastic tumor accounting for less than 1% of all bone tumors; approximately 10% to 12% of cases occur in the maxillofacial skeleton. This case report describes the clinical, imaging, and histopathologic findings of an atypical osteoblastoma occurring in the mandible of a 60-year-old man. The characteristics of the lesion and the differential diagnosis from other bone pathoses are reviewed.

MRI patterns indicate treatment success and tumor relapse following radiofrequency ablation of osteoblastoma.

Purpose: To explore the typical magnetic resonance imaging (MRI) pattern of osteoblastoma (OB) after radiofrequency ablation (RFA) treatment and to identify signs indicating treatment success or relapse.Materials and methods: Forty-four follow-up MRI examinations of 15 patients with OB who had undergone 19 RFA procedures were analyzed retrospectively. An early follow-up group (1-4 months after RFA) and a late follow-up group (8-131 months after RFA) were established. The groups were further subdivided according to treatment success. Images were analyzed for the presence of central nidus enhancement (CNE), peripheral nidus enhancement (PNE), perifocal bone marrow edema (PBME) and fatty nidus conversion (FNC).Results: The early follow-up MRI image from every patient in the treatment success group exhibited a target-like appearance with negative CNE and positive PNE or PBME. PNE and PBME were observed in 93% and 71% of the early follow-up images, respectively. A target-like appearance was observed in 25% of the late follow-up images, and PNE and PBME were each observed in 20% of these images. FNC was not observed in the early follow-up images, but was seen in 55% of the late follow-up images. All three MRI images of the patients exhibiting clinical recurrence demonstrated strong CNE, PNE and extensive PMBE, which was in contrast to the images of the patients exhibiting treatment success.Conclusion: A target-like appearance of OB in early follow-up MRI examination indicates treatment success. PNE and PBME typically reduce over time and can lead to FNC in successfully treated patients. CNE recurrence, PNE and extensive PBME are signs of relapse.

Recurrent lumbar-origin osteoblastoma treated with multiple surgery and carbon ion radiotherapy: a case report.

BACKGROUND: Although osteoblastoma is an uncommon benign bone tumor, it sometimes behaves in a locally aggressive fashion. We herein report a case of recurrent lumbar spine osteoblastoma that was treated by repeated surgery and carbon ion radiotherapy. CASE PRESENTATION: A 13-year-old Japanese girl presented with left side lumbar pain. Computed tomography and magnetic resonance imaging of the lumbar spine demonstrated a tumorous lesion in the left side pedicle of L4. Although gross total resection of the mass, including the nidus, was performed in the initial surgery, recurrence was observed repeatedly in the short term and the pathological diagnosis of all of the resected tumors was conventional osteoblastoma. We finally performed carbon ion radiotherapy after the patient's 3rd palliative operation, and achieved a good outcome. No further recurrence has been observed in 10 years of follow-up. CONCLUSION: We performed carbon ion radiotherapy for a case of recurrent spinal osteoblastoma and achieved a good outcome without recurrence at 10 years after carbon ion radiotherapy treatment. To the best of our knowledge, this is the first case of osteoblastoma that was treated with carbon ion radiotherapy after multiple surgeries.

Imaging algorithm and multimodality evaluation of spinal osteoblastoma.

BACKGROUND: To analyze the features of CT, MRI and PET/CT and their diagnostic value for spinal osteoblastomas (OBs). METHODS: The radiological and clinical data of 21 patients with histopathologically-confirmed spinal OBs were analyzed retrospectively. RESULTS: Sixteen of the 21 cases were benign and 5 were aggressive OBs. Tumors were located in the lumbar (n = 11), cervical (n = 4), thoracic (n = 5), and sacral (n = 1) spinal regions. Nineteen cases were centered in the posterior elements of the spine, 13 of which extended into the vertebral body. Punctate or nodular calcifications were found in all cases on CT with a complete sclerotic rim (n = 12) or incomplete sclerotic rim (n = 8). The flare phenomenon (indicative of surrounding tissue inflammation) was found in 17/21 cases on CT, thin in 11 cases and thick in 6 cases, and in 19/19 cases on MRI, thin in 1 case and thick in 18 cases. On 18F-FDG PET/CT, all cases (8/8) were metabolically active with the SUVmax of 12.3-16.0; the flare sign was observed in 8 cases, including 7 cases of hypometabolism and 1 case of coexistence of hypermetabolism and hypometabolism. Based on CT, 3, 12, and 6 cases were classified as Enneking stage 1, 2 and 3, respectively. Of 19 cases with MRI, 1 and 18 cases were classified as Enneking stage 2 and 3, respectively. CONCLUSIONS: Spinal OB has multiple unique characteristic radiological features. Although a larger sample size is needed, combining CT, MRI and PET may be beneficial to optimize preoperative diagnosis and care of patients with OBs.

Percutaneous cryoablation of osteoblastoma in the proximal femur.

A 37-year-old man presented with a 2-year history of left hip pain. Pretherapeutic imaging demonstrated a 4 cm osteoblastoma located in the intertrochanteric region of the proximal femur, surrounded by extensive bone marrow edema. After multidisciplinary meeting, percutaneous cryoablation was decided and performed under computed tomography guidance using three cryoprobes to match the exact size and shape of the tumor, resulting in complete resolution of symptoms. Magnetic resonance imaging follow-up demonstrated resolution of the bone marrow edema pattern and ingrowth of fat at the periphery of the ablation zone consistent with long-term healing of the tumor.

Surgical Excision of Thoracic Osteoblastoma with Secondary Aneurysmal Bone Cyst from a 12-Year-Old Child.

INTRODUCTION: Osteoblastoma is a primary benign tumour which commonly presents in the younger population during the second decade of life. However, more aggressive osteoblastomas may present with features of aneurysmal bone cyst, and these can occur at uncommon locations. CASE PRESENTATION: We report the case of a 12-year-old child having an osteoblastoma on the left side of T11 with secondary aneurysmal bone cyst presenting with neurological deficits and myelopathic symptoms. Surgical debulking of the lesion with decompression laminectomy and posterior instrumentation of the spine was performed. The child is currently recovering well with improvement of neurological deficits. DISCUSSION/CONCLUSION: Osteoblastoma with aneurysmal bone cyst of the thoracic spine is a rare condition with few reports in the literature, and surgical intervention with complete excision has been demonstrated here with recovery of neurological function.

[Molecular pathology in the diagnosis of bone tumors: current concepts]. / Molekulare Pathologie in der Diagnostik der Knochentumoren: Aktueller Stand.

The integrative evaluation of histology and corresponding imaging is essential for the classification of bone tumors. Until a few years ago, there were hardly any molecular markers that could be used for diagnostic purposes. However, exome- and genome-wide sequencing analyses have since uncovered a number of tumor-specific aberrations that can be very helpful in ambiguous cases. In addition to characteristic gene mutations (e.g. H3F3A and H3F3B in giant-cell tumors and chondroblastomas), the detection of fusion transcripts (e.g. structural rearrangements in the AP­1 transcription factors FOS and FOSB in osteoid osteomas and osteoblastomas) plays an increasing role. The article gives an overview of the current state of knowledge of the most important alterations in bone tumors.

Aggressive Osteoblastoma Involving the Navicular Bone of Foot: A Rare Tumor in a Unique Location.

Aggressive osteoblastoma (AO) is a rare variant of osteoblastoma characterized histologically by epithelioid osteoblasts and clinically by local recurrences if not excised completely. Aggressive osteoblastoma has been described in various unusual sites; however, based on our search of the literature, involvement of the tarsal navicular has not been previously described. Herein, we report what we believe to be the first case of aggressive osteoblastoma involving the tarsal navicular in a 35-year-old woman. The tumor showed osteoid surrounded by epithelioid cells along with numerous osteoclastic giant cells. Absence of necrosis, mitosis, and infiltration into the surrounding native bone helped rule out the possibility of low-grade osteosarcoma.

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.