Young adults are most frequently affected by OB, and patients typically seek medical attention for dull bone pain. Soft tissue and bony swelling may be noted at the site of the lesion. A general predilection for the axial skeleton has been observed [4], and up to 40% of cases involve the spine, mainly the vertebral arches of the lumbar region [5]. Nevertheless, OB may also develop in the appendicular skeleton, affecting the long bones of arms and legs or distal parts of the limbs [6].

OB exert local mass effects and accordingly, patients may present with spinal cord compression, radiculopathy, visual impairment and additional neurological deficits [7], stiffness and reduced joint motion ranges, among others. Lateral deviations of the spine and other deformities may be observed [8].

• Dysphagia

  We present the first known case of osteoblastoma arising in the hyoid bone, in a patient who presented with a neck mass and dysphagia. [ncbi.nlm.nih.gov]

  Laryngeal osteoblastoma usually presents as an inflammatory tumour which, as it progresses slowly, causes dyspnoea, dysphagia, and/or dysphonia. [elsevier.es]

• Abdominal Mass

  The patient subsequently developed a cutaneous lower abdominal mass that was diagnosed as an osteosarcoma. Meanwhile, the petrous apex tumor continued to grow despite treatment until the patient died from the burden of disease. [ncbi.nlm.nih.gov]

• Progressive Hearing Loss

  We report an interesting and rare case of aggressive osteoblastoma, with progressive hearing loss and facial palsy, involving the mastoid process of temporal bone and middle ear along with the description of cyto-morphological features. [ncbi.nlm.nih.gov]

  When it arises from temporal bone and middle it may cause progressive hearing loss. [ijpmonline.org]

• Photophobia

  A 31 year old man came to our attention with a 7 month history of diplopia, photophobia, frontal headhaches and progressive exophthalmos with proptosis of the left eye. [ncbi.nlm.nih.gov]

• Visual Impairment

  OB exert local mass effects and accordingly, patients may present with spinal cord compression, radiculopathy, visual impairment and additional neurological deficits, stiffness and reduced joint motion ranges, among others. [symptoma.com]

• Subcutaneous Mass

  Although clinical presentation can vary depending on location, cranial osteoblastoma usually presents as a painful, non-mobile, subcutaneous mass or swelling. [ncbi.nlm.nih.gov]

• Back Pain

  Surgical resection of the lesion confirmed a benign osteoblastoma. 12 months follow-up revealed disappearance of right back pain. [ncbi.nlm.nih.gov]

• Ankle Pain

  We report a young male, presenting as chronic ankle pain, with a radiolucent lesion with a thick periosteal shell in the body of the talus. Analysis of clinical, radiological and histological findings confirmed the diagnosis of osteoblastoma. [ncbi.nlm.nih.gov]

  Chb 2 The Foot & Ankle Journal 1 (6): 5 ISSN 1941-6806 doi: 10.3827/faoj.2008.0106.0005 Case History An 8 year old boy presents with history of ankle pain for 4 months. His pain is mainly to the anterior aspect of the ankle joint. [faoj.org]

• Left Shoulder Pain

  We present a case of a 19-year-old man with left shoulder pain for 1 year, with associated infraclavicular swelling for 8 months. Examination revealed a tender, bony, hard swelling measuring 3 4 cm. [ncbi.nlm.nih.gov]

• Claustrophobia

  The lengthy duration of an MRI examination and a history of claustrophobia in some patients are limiting the use of MRI. [en.wikipedia.org]

• Facial Swelling

  A 7-year-old male patient visited our department with chief complaints of left facial swelling and pain. A panoramic radiograph showed a homogeneous radio-opaque expansile lesion in the left maxilla. [ncbi.nlm.nih.gov]

  CASE REPORT A 40 year-old male was referred to our University, with asymptomatic facial swelling and nasal obstruction. The patient reported that the lesion had been present for at least 8 years and has been showing slow but progressive enlargement. [arquivosdeorl.org.br]

• Neck Mass

  We present the first known case of osteoblastoma arising in the hyoid bone, in a patient who presented with a neck mass and dysphagia. [ncbi.nlm.nih.gov]

• Radiculopathy

  Their presentation can vary between diffuse pain, restriction of neck movements, torticollis, radiculopathy, and myelopathy. Complete excision is the best treatment to achieve a cure, but recurrence is not uncommon. [ncbi.nlm.nih.gov]

  OB exert local mass effects and accordingly, patients may present with spinal cord compression, radiculopathy, visual impairment and additional neurological deficits, stiffness and reduced joint motion ranges, among others. [symptoma.com]

  Neurologic symptoms, such as cranial nerve palsies, myelopathy, neuralgia, radiculopathy, paraparesis or paraplegia, may be associated if the spine is involved. [orpha.net]

• Cranial Nerve Involvement

  Clinical symptoms are non-specific and cranial nerve involvement is uncommon. The cytomorphological features of osteoblastoma are not very well defined and the experience is limited to only few reports. [ncbi.nlm.nih.gov]

• Generalized Tonic-Clonic Seizure

  The patient presented with a history of headache, vomiting and generalized tonic-clonic seizures. CT scan showed a hyperdense lesion in the posterior third ventricle with obstructive hydrocephalus. [ncbi.nlm.nih.gov]

Diagnostic imaging is required to confirm the presence of an osseous mass, to determine its extension and to identify possibly compromised adjacent structures. Plain radiography and computed tomography are most commonly employed and yield reliable results. Here, OB present as discrete lesions comprising both lytic and sclerotic regions [9]. Soft tissue involvement may be better assessable applying other imaging techniques.

A histopathological examination of biopsy specimens is crucial for the diagnosis of OB. In this context, it is important to obtain representative samples that ideally measure several millimeters in size. Fine-needle aspirates are usually insufficient. OB are hypocellular, mineralized tumors consisting of irregular, largely immature trabecular bone [7]. Giant cells may be present. There are no apparent differences between central and peripheral areas of the tumor. Lesions are well demarcated, and this feature helps to distinguish OB from osteosarcoma. However, the transition from benign OB to malignant osteosarcoma is smooth and aggressive types of OB have been described [10].

Based on radiological findings and histopathological analyses alone, the distinction between OB and osteoid osteoma may pose a major challenge. Still, a precise diagnosis is of major prognostic and therapeutic relevance: OB have considerable malignant potential, may show locally aggressive behavior,and recurrence is more likely than in patients diagnosed with osteoid osteoma [5]. Clinical criteria should be considered to support a tentative diagnosis of either bone tumor [4]:

• OB usually develop in the axial skeleton, while osteoid osteomas primarily affect the long bones of the limbs.
• Persistent bone pain is characteristic of OB, whereas osteoid osteoma patients frequently experience pain that worsens at night.
• In patients suffering from osteoid osteoma, pain may be relieved by salicylates, but this is rarely the case in individuals suffering from OB.
• Both are most commonly diagnosed in young adults but may affect patients of any age.

Osteoblastoma (OB) is a rare type of neoplasm, accounting for approximately 1% of primary bone tumors [1]. OB are benign tumors originating from osteoblasts, and they are characterized by their ability to produce osteoid. Thus, they form large masses with diameters exceeding 2 cm that exert local mass effects on adjacent tissues. Because OB most frequently affect the axial skeleton, central nervous system compromise is frequently seen in affected individuals. Furthermore, OB have been reported to undergo malignant transformation [2]. Still, OB patients generally have a good prognosis and most of them are cured by means of a complete surgical resection of the neoplasm [3].

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9. Pelargos PE, Nagasawa DT, Ung N, et al. Clinical characteristics and diagnostic imaging of cranial osteoblastoma. J Clin Neurosci. 2015; 22(3):445-449.
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