Cancer, Osteoblastoma

Article Author:
Faten Limaiem
Article Author:
Doug Byerly
Article Editor:
Rahulkumar Singh
5/27/2020 5:54:43 PM
PubMed Link:
Cancer, Osteoblastoma


Osteoblastoma is an uncommon benign bone-forming neoplasm which accounts for about 1% of all primary bone tumors. It commonly arises in the posterior elements of the spine and the sacrum. Accurate diagnosis of osteoblastoma is critical in determining the appropriate treatment modality and prognosis. In most cases, the basis for diagnosis is from clinical, radiological, and mainly histopathological examination. Osteoblastomas have a variable radiologic appearance ranging from indolent to very aggressive.[1] In general, osteoblastoma has a good prognosis, and patients are often cancer-free after surgical treatments of intralesional curettage or marginal en bloc resection.[2]


The exact etiology of osteoblastoma is still unknown, and so are the predisposing factors.


Osteoblastoma is a rare benign neoplasm, accounting for about 1% of all primary bone tumors. It affects mainly adolescents and young adults (mean age, 20 years) with a male predominance (2.5 to 1). Osteoblastoma can involve any bone. It commonly arises in the posterior elements of the spine and the sacrum (40 to 55%).[3] In the appendicular sites, the proximal femur, distal femur, and proximal tibia are the most frequent. Osteoblastoma less commonly involves the tarsal bones (talus and calcaneum). The majority of the cases are intraosseous (medullary).


Cytogenetic studies of osteoblastoma are few with the characterization of only six cases. These analyses have demonstrated near-diploid complements with unrelated rearrangements.[4]


Macroscopic examination:

Osteoblastoma has a copious vascular supply and therefore appears red or red-brown, often with a gritty or sandpaper consistency. The average size is 3 to 3.5 cm, with maximum diameter up to 15 cm.[5][3] The tumor is usually round to oval with a thinned cortex and always with a thin periosteal reactive bone shell if there is cortex is destruction. The border between the tumor and medullary cavity is sharp, often with some reactive bone. The tumor has a ''pushing'' border than a permeative or infiltrative border against the endosteal cortical surface and trabecular bone of the marrow.[3]

Histopathological examination:

Osteoblastoma has identical histological features to osteoid osteoma. The tumor is composed of woven bone spicules or trabeculae. These spicules are haphazardly arranged and have a lining of a single layer of osteoblasts. The vascularity is rich, often with extravasated erythrocytes. Osteoblasts may have mitoses, but they are not atypical. Diffusely scattered osteoclast-type, multinucleated giant cells are often present.[3] Osteoblastomas do not infiltrate or isolate pre-existing lamellar bone structures as do osteosarcomas, so special attention should be given to the border between preexisting cortex or marrow trabeculae. The lesion can include areas of secondary aneurysmal cysts.  The term epithelioid osteoblastoma, previously known as aggressive osteoblastoma, has been used for cases of osteoblastoma with large, plump osteoblasts with a prominent nucleus and nucleoli, sometimes with mitoses.[6][7]

Dorfmann and Weiss classified osteoblastomas into four groups in 1984.[6]

1- Low-grade osteosarcomas (osteoblastoma like osteosarcoma).

2- Pseudomalignant osteoblastomas.

3- Osteoblastomas that have undergone malignant transformation to osteosarcoma. Some authors believe that these should belong to osteoblastoma like osteosarcomas.

4- Aggressive osteoblastoma: Aggressive osteoblastomas have characteristics intermediate between those of osteoblastoma and low-grade osteosarcoma. Some authors have considered this group as malignant osteoblastoma.

To date, the WHO has not subclassified osteoblastoma. However, some intermediate-grade osteoblastomas lying on the borderline between the benign osteoblastoma and the osteosarcoma have been found, including aggressive osteoblastomas with locally aggressive behavior.[8]


Beta-catenin can be used to differentiate between osteoblastoma and osteosarcoma. Osteoblastoma is characterized by nuclear beta-catenin staining whereas cytoplasmic or membranous staining of beta-catenin suggests osteosarcoma.[9]

A recent study has recommended using hypoxia-related microRNA-210 as a successful diagnostic marker for discriminating osteoblastoma and osteosarcoma.[10]

History and Physical

Osteoblastomas generally grow slowly with minimal symptomatology, but aggressive lesions may cause severe symptoms such as soft tissue edema, joint stiffness, and contracture. Pain is the most common presenting symptom, and diagnosis may be delayed up to two years from the onset of symptoms.[1] Osteoblastomas of the spine have similar symptoms to that of osteoid osteoma; namely back pain, scoliosis, and nerve root compression.[11] The appendicular tumors also produce pain and/or swelling, but these symptoms may be mild enough to last for months before the patient will see a clinician. Toxic osteoblastoma is a very rare variant of osteoblastoma associated with systemic symptoms, including fever, anorexia, and weight loss.


Several imaging modalities are available for establishing the diagnosis of osteoblastoma. They include:

  • Plain radiographs
  • Computed tomography (CT)
  • Magnetic resonance imaging (MRI)

On imaging, osteoblastoma may be difficult to distinguish from osteoid osteoma.[1] Imaging techniques generally show osteoblastomas as being osteolytic tumors; however, due to osteoid and bone components, osseous type mineralization may be seen.[12] The lesions are usually well-circumscribed, central to slightly eccentric in long bones, rounded or ovoid, and expansile.[5][13]


On plain radiography, an osteoblastoma appears as a lucent, expansile lesion with a varying degree of sclerosis, usually in the neural arch.

Computed tomography scan (CT):

CT can also demonstrate cortical breakthrough if the osteoblastoma is aggressive. CT better demonstrates the lesion as well as potential matrix mineralization or trabecula 

Magnetic resonance imaging (MRI):

On MRI, osteoblastomas have low to isointense T1 signal intensity and isointense to high T2 signal intensity, and they enhance. 

Studies using technetium-99m scintigram have shown an increased uptake in the mass,[14] and FDG-PET studies have revealed a high uptake in the tumor in spite of its pathologically benign features.[14]

Treatment / Management

The treatment of patients with osteoblastoma is surgery. The lesion can be removed with intralesional curettage or wide resection, depending on the clinical situation, location within the bone, and suspicion of malignancy.[15][16] Recurrence rates vary with the surgical approach, and wide resection correlates with lower recurrence rates. There is no definite role for adjuvant chemotherapy or radiotherapy. Because of the risk of transformation into osteosarcoma, radiotherapy is increasingly not a treatment of choice.[17][14]

Differential Diagnosis

Histological differential diagnosis [3]:

  • Osteoid osteoma
  • Aneurysmal bone cyst
  • Giant cell tumor of bone
  • Osteoma with osteoblastoma-like features
  • Osteoblastoma-like osteosarcoma

Radiological differential diagnosis [1]:

  • Osteoid osteoma
  • Aneurysmal bone cyst
  • Infection
  • Osteosarcoma
  • Metastasis


The prognosis of osteoblastoma is excellent with a local recurrence rate of about 15% to 20%[3] Therefore, long-term follow-up of patients with osteoblastoma is essential due to recurrence.[[8] Osteoblastomas located near the central neural axis has a worse prognosis due to the difficulty of complete excision. Progression of osteoblastoma to osteosarcoma is exceptional but has been reported[5][3]

Several factors can influence the diagnosis of aggressive osteoblastoma, including [8]:

  • Radiographic
  • Clinical
  • Pathologic features

Enhancing Healthcare Team Outcomes

Osteoblastoma is ideally managed by an interprofessional team that consists of orthopedists, radiologists, and pathologists. Correlation between gross, radiographic, and microscopic features of the lesion is crucial to establish the definitive diagnosis of osteoblastoma. Postoperatively, patients require long term follow-up due to the possibility of tumor recurrence and malignant transformation. Oncology nurse practitioners and specialty trained nurses are involved in follow up, patient and family education, and provide status reports to the team.

  • Image courtesy S Bhimji MD
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      Image courtesy S Bhimji MD


[1] Sharma V,Chew FS,Hoch B, Periosteal osteoblastoma: Multimodal imaging of a rare neoplasm. Radiology case reports. 2009;     [PubMed PMID: 27307837]
[2] Atesok KI,Alman BA,Schemitsch EH,Peyser A,Mankin H, Osteoid osteoma and osteoblastoma. The Journal of the American Academy of Orthopaedic Surgeons. 2011 Nov;     [PubMed PMID: 22052644]
[3] Lucas DR, Osteoblastoma. Archives of pathology     [PubMed PMID: 20923301]
[4] Giannico G,Holt GE,Homlar KC,Johnson J,Pinnt J,Bridge JA, Osteoblastoma characterized by a three-way translocation: report of a case and review of the literature. Cancer genetics and cytogenetics. 2009 Dec;     [PubMed PMID: 19963118]
[5] Lucas DR,Unni KK,McLeod RA,O'Connor MI,Sim FH, Osteoblastoma: clinicopathologic study of 306 cases. Human pathology. 1994 Feb;     [PubMed PMID: 8119712]
[6] Dorfman HD,Weiss SW, Borderline osteoblastic tumors: problems in the differential diagnosis of aggressive osteoblastoma and low-grade osteosarcoma. Seminars in diagnostic pathology. 1984 Aug;     [PubMed PMID: 6600112]
[7] Kenan S,Floman Y,Robin GC,Laufer A, Aggressive osteoblastoma. A case report and review of the literature. Clinical orthopaedics and related research. 1985 May;     [PubMed PMID: 3978963]
[8] Lu ZH,Cao WH,Qian WX, Aggressive osteoblastoma of the temporal bone: a case report and review of the literature. Clinical imaging. 2013 Mar-Apr;     [PubMed PMID: 23465999]
[9] Wan Y,Zhao W,Jiang Y,Liu D,Meng G,Cai Y, β-catenin is a valuable marker for differential diagnosis of osteoblastoma and osteosarcoma. Human pathology. 2014 Jul;     [PubMed PMID: 24746516]
[10] Riester SM,Torres-Mora J,Dudakovic A,Camilleri ET,Wang W,Xu F,Thaler RR,Evans JM,Zwartbol R,Briaire-de Bruijn IH,Maran A,Folpe AL,Inwards CY,Rose PS,Shives TC,Yaszemski MJ,Sim FH,Deyle DR,Larson AN,Galindo MA,Cleven AGH,Oliveira AM,Cleton-Jansen AM,Bovée JVMG,van Wijnen AJ, Hypoxia-related microRNA-210 is a diagnostic marker for discriminating osteoblastoma and osteosarcoma. Journal of orthopaedic research : official publication of the Orthopaedic Research Society. 2017 May;     [PubMed PMID: 27324965]
[11] Nemoto O,Moser RP Jr,Van Dam BE,Aoki J,Gilkey FW, Osteoblastoma of the spine. A review of 75 cases. Spine. 1990 Dec;     [PubMed PMID: 2149206]
[12] Jackson RP, Recurrent osteoblastoma: a review. Clinical orthopaedics and related research. 1978 Mar-Apr;     [PubMed PMID: 657629]
[13] Frassica FJ,Waltrip RL,Sponseller PD,Ma LD,McCarthy EF Jr, Clinicopathologic features and treatment of osteoid osteoma and osteoblastoma in children and adolescents. The Orthopedic clinics of North America. 1996 Jul;     [PubMed PMID: 8649737]
[14] Shimizu N,Sakata K,Yamamoto I, Benign osteoblastoma of the temporal bone: Case report and review of the literature. Surgical neurology. 2006 Nov;     [PubMed PMID: 17084206]
[15] Ozaki T,Liljenqvist U,Hillmann A,Halm H,Lindner N,Gosheger G,Winkelmann W, Osteoid osteoma and osteoblastoma of the spine: experiences with 22 patients. Clinical orthopaedics and related research. 2002 Apr;     [PubMed PMID: 11953633]
[16] Golant A,Lou JE,Erol B,Gaynor JW,Low DW,Dormans JP, Pediatric osteoblastoma of the sternum: a new surgical technique for reconstruction after removal: case report and review of the literature. Journal of pediatric orthopedics. 2004 May-Jun;     [PubMed PMID: 15105730]
[17] Doshi SV,Frantz TD,Korol HW, Benign osteoblastoma of the temporal bone: case report and literature review. American journal of otolaryngology. 2001 May-Jun;     [PubMed PMID: 11351292]