Epithelioid Osteoblastoma Research Articles

A benign tumor of substantial size: Mandibular epithelioid osteoblastoma in a socioeconomically challenged patient

Epithelioid osteoblastoma (EOB) is a rare, benign bone tumor characterized by the proliferation of atypical epithelioid osteoblasts within a vascular stroma. It typically presents as a slow-growing painful mass and requires careful differentiation from more aggressive lesions like osteosarcoma for appropriate management. We present a case of an otherwise healthy 30-year-old man who presented with a mandibular EOB measuring 23 cm × 17 cm x 19 cm, causing significant disfigurement and functional impairment. Surgical management involved radical resection and immediate reconstruction using an osteocutaneous fibula free flap. The case emphasizes the importance of multidisciplinary care, advanced surgical planning, and the impact of socioeconomic factors on healthcare access and outcomes.

Osteoblastoma Recurring as High-grade Osteosarcoma

Abstract Introduction/Objective Osteoblastoma is a benign, bone-forming neoplasm that presents as a well-circumscribed lesion amenable to excision. The prognosis is good despite a 20% recurrence risk. Malignant transformation is very rare. Osteoblastoma-like osteosarcoma is a rare form of osteosarcoma that shares similar clinical, radiographic, and pathological characteristics Methods/Case Report A 24-year-old female presented with a large palpable mass in the posterior occiput. The lesion progressively enlarged over 2 years, finally becoming symptomatic. Magnetic resonance imaging demonstrated an extradural posterior fossa expansile skull mass measuring 6.0 x 5.7 x 4.7 cm that showed multiple fluid/fluid levels. The mass was resected. Pathology demonstrated a well-circumscribed neoplasm that was cellular and composed of large polyhedral osteoblasts with eccentric oval nuclei and abundant amphophilic cytoplasm. Tumor cells were intimately associated with numerous small interconnecting, irregular bony trabeculae. Scattered mitotic figures of normal configuration were noted. The findings were compatible with an epithelioid osteoblastoma with prominent secondary aneurysmal bone cyst-like changes. The patient was lost to follow-up but presented 3 years later with severe migraines. Imaging demonstrated a large heterogeneous enhancing mass centered about the occipital cranioplasty with both intracranial and extracranial components. Reexcision was performed. Sections showed a well- circumscribed tumor, delineated by a rim of subperiosteal reactive bone, with an epithelioid morphology. However, it also demonstrated areas of necrosis, extensive sheet-like growth, conspicuous mitoses, and cytological atypia not seen in the previous specimen. Therefore, diagnosis of osteoblastoma-like osteosarcoma was rendered after expert consultation. Results (if a Case Study enter NA) NA Conclusion This case highlights the exceedingly rare evolving nature of osteoblastomas and their high-grade transformation potential.

A case of epithelioid osteoblastoma of the thoracic vertebra in a 12-year-old male: a case report and review of literature

Introduction and importance: Osteoblastoma (OB) is a rare benign bone tumor, representing less than 1% of all bone neoplasms. In contrast to the typical OB, a smaller subset known as ‘epithelioid osteoblastoma (EO)’ exhibits a distinctive inclination for local invasion and recurrence. This rare variant can pose diagnostic challenges, particularly due to its unclear clinical and radiological presentation. Case presentation: This study details a clinical case of a 12-year-old boy experiencing pain from a lytic bone tumor located in the thoracic vertebrae (T3–T4), initially suggesting malignancy. Following extensive curettage, histopathological analysis confirmed the diagnosis of EO through immunohistochemical staining. Subsequent follow-up at 3 months revealed the absence of no pain or recurrence of the lesion. Clinical discussion: Distinguishing EO from a malignant tumor requires a multidisciplinary approach, considering clinical, radiographic, and histological features that differentiate the two entities. Conclusion: The goal of this case presentation is to increase awareness regarding this recurrent tumor variant, which poses diagnostic challenges, particularly in distinguishing it from malignant tumors, including osteosarcoma.

Epithelioid Osteoblastoma Combined with Aneurysmal Bone Cyst Originating from the Right Temporal Bone and The Greater Wing of the Sphenoid Bone.

Epithelioid Osteoblastoma Combined with Aneurysmal Bone Cyst Originating from the Right Temporal Bone and The Greater Wing of the Sphenoid Bone.

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 6.5cm in the greatest diameter (mean=4.1cm) 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.

Loss of NF2 defines a genetic subgroup of non-FOS-rearranged osteoblastoma.

Osteoblastoma is a locally aggressive tumour of bone. Until recently, its underlying genetic features were largely unknown. During the past two years, reports have demonstrated that acquired structural variations affect the transcription factor FOS in a high proportion of cases. These rearrangements modify the terminal exon of the gene and are believed to stabilise both the FOS transcript and the encoded protein, resulting in high expression levels. Here, we applied in‐depth genetic analyses to a series of 29 osteoblastomas, including five classified as epithelioid osteoblastoma. We found recurrent homozygous deletions of the NF2 gene in three of the five epithelioid cases and in one conventional osteoblastoma. These events were mutually exclusive from FOS mutations. Structural variations were determined by deep whole genome sequencing and the number of FOS‐rearranged cases was less than previously reported (10/23, 43%). One conventional osteoblastoma displayed a novel mechanism of FOS upregulation; bringing the entire FOS gene under the control of the WNT5A enhancer that is itself activated by FOS. Taken together, we show that NF2 loss characterises a subgroup of osteoblastomas, distinct from FOS‐rearranged cases. Both NF2 and FOS are involved in regulating bone homeostasis, thereby providing a mechanistic link to the excessive bone growth of osteoblastoma.

Clinicopathologic study of 6 cases of epithelioid osteoblastoma of the jaws with immunoexpression analysis of FOS and FOSB.

The aim of this study was to describe the clinicopathologic features of a series of gnathic epithelioid osteoblastomas. As high levels of Proto-oncogene c-Fos proteins resulting from FOS-FOSB translocation were recently demonstrated in osteoblastomas, we also evaluated the immunoexpression of these proteins. Records of all cases of epithelioid osteoblastoma of the jaws were retrieved from oral pathology services, and their clinicopathologic and immunohistochemical data were collected. Immunohistochemistry was also performed by using anti-FOS and anti-FOSB antibodies. Six cases of epithelioid osteoblastomas were obtained, 4 in men and 2 in women, and they were mainly located in the posterior body of the mandible (n = 4). Radiographically, the tumors showed mixed radiolucent and radiopaque images, most with poorly defined margins. Microscopically, large epithelioid cells with eccentrically located nuclei predominated among osteoid and immature bone trabeculae. Sharp delineation from adjacent normal bone was observed in all cases. FOS immunostaining was diffuse and strong in the cytoplasm and nucleus of neoplastic cells in all cases, whereas FOSB was only focally positive, with few epithelioid osteoblasts showing nuclear staining. Although epithelioid osteoblastomas of the jaws are locally aggressive, widespread metastasis does not occur, and, as with conventional osteoblastomas, there is wide expression of the FOS protein.

Osteoma osteoide raquídeo recidivante en forma de osteoblastoma agresivo

We report an uncommon case of osteoid osteoma recurring as an aggressive osteoblastoma of the spine. A 15-years-old male consulted in our department with long-term painful scoliosis. The CT-scans and MRI revealed a sclerotic bone forming tumor of 7mm diameter consistent with a osteoid osteoma. A percutaneous radiofrequency ablation was performed with complete resolution of the symptoms. After 6 months, the symptoms recurred. A new CT and a MRI showed a growth of the nidus on the right L4 lamina, with a size of 15mm. Therefore, a marginal resection by laminectomy of L4 was performed. Pathology confirmed an epithelioid osteoblastoma. A year later, subsequent imaging studies showed a new recurrence with aggressive features and invasion of the spinal canal. The patient then underwent an "in block surgery" needing concurrent stabilization of the spine. Histopathology confirmed the diagnosis of epithelioid osteblastoma.

A rare case of aggressive osteoblastoma in maxilla

AbstractOsteoblastoma is a benign osteogenic bone tumour. Despite having a benign character, a small subgroup referred to as aggressive or epithelioid osteoblastoma can exhibit locally aggressive behaviour. Herein, we report a 45‐year‐old man who presented with a rapidly growing palatal and maxillary mass that resulted in difficulty with respiration and oral feeding. Following radiological evaluation and incisional biopsy based on the prediagnosis of aggressive osteoblastoma, total maxillectomy was performed. Histopathological examination revealed an expansile bone‐forming tumour without any atypical mitosis, necrosis, pleomorphism or hyperchromasia and it was interpreted as aggressive osteoblastoma. The differential diagnosis includes low‐grade osteoblastoma‐like osteosarcoma, and there is an ongoing debate about the proper classification and diagnosis. Proper treatment should include surgical excision of the lesion, reconstruction of the surgical site and close follow‐up for possible recurrence. This case is a well‐demonstrated example of multidisciplinary approach to diagnosis and treatment of a rare and challenging phenomenon.

Multinodular Epithelioid Osteoblastoma of the Mandible

Multinodular epithelioid osteoblastoma is a rare variant of osteoblastoma characterized by numerous nodules of epithelioid osteoblasts surrounding bony trabeculae as well as clusters of epithelioid osteoblasts without osteoid formation. It commonly occurs in gnathic bones of the face and spine, and has a male predominance. To date, only 26 cases of multinodular epithelioid osteoblastoma have been reported in the literature. Here, we add an additional case to those previously reported. An 18-year-old male patient presents with a periapical radiolucency in the region of vital tooth #30. The surgeon’s differential diagnosis for this radiolucent lesion was ameloblastoma versus cyst. An incisional biopsy of the lesion revealed well-vascularized fibrous connective tissue containing a multinodular tumor composed of collections of epithelioid cells with osteoblastic differentiation surrounding zones of hyalinization and bony trabeculae. Multinucleated giant cells and rare mitotic figures were noted. Additionally present within the tumor were clusters of epithelioid osteoblasts without bony trabeculae. Residual immature viable bone trabeculae were noted surrounding the tumor. A diagnosis of multinodular epithelioid osteoblastoma was rendered. In this paper, we present a rare case of multinodular osteoblastoma of the mandible and a review of the literature. We will highlight the unique histological features that help differentiate this tumor from tumors classified as conventional osteoblastoma, aggressive osteoblastoma, epithelioid osteoblastoma and most importantly, low-grade osteosarcoma.

Aggressive (Epithelioid) Osteoblastoma Arising in Soft Tissue

Aggressive (epithelioid) osteoblastoma arising in soft tissue has never been described. It is important to differentiate this benign osteoblastoma, a potentially locally aggressive tumor, from extraskeletal osteosarcoma. This report describes an aggressive (epithelioid) osteoblastoma arising in a focus of heterotopic ossification in the axilla of a 21-year-old man.