Jordi | Journal of Oral Diagnosis Online Submission Review an Article SOBEP - Sociedade Brasileira de Estomatologia e Patologia Oral
Volume 2 - 2017


Original Article

DOI: 10.5935/2525-5711.20170039

An unusual presentation of osteoblastoma

Victor Perez Teixeira1,2; José Narciso Rosa Assunção Júnior1; Letícia Almeida Oliveira1; Ana Maria Hoyos Cadavid3; Celso Augusto Lemos Júnior4; João Alberto Lopes Sousa Júnior5

1. UNIMES, School of Dentistry - Santos - São Paulo - Brasil
2. UNIMES, School of Medicine - Santos - São Paulo - Brasil
3. FOUSP, Department of Oral Pathology, School of Dentistry - São Paulo - São Paulo - Brasil
4. FOUSP, Department of Stomatology, School of Dentistry - São Paulo - São Paulo - Brasil
5. Hospital Dr. Luis Camargo da Fonseca e Silva, Serviço de Cirurgia de Cabeça e Pescoço - Cubatão - São Paulo - Brasil

Corresponding authors: Victor Perez Teixeira
E-mail 1: teixeira.victorp@gmail.com
E-mail 2: victorpteixeira@hotmail.com

Article received on July 18, 2017.
Article accepted on October 5, 2017.

 

ABSTRACT

Osteoblastoma is a rare benign bone tumor that accounts for less than 1% of all primary bone tumors. Due to a low occurrence and varied histopathological aspects, this pathology becomes a diagnostic challenge. Therefore, our objective of reporting a case of osteoblastoma in the maxilla is to discuss another presentation of this tumor. Male patient, suffering from leucoderma, 50 years old, presented an expansion in right superior vestibular groove with pain during palpation and an extensive osteolytic lesion in the right maxilla, of solid content, observed in computed tomography. With an anatomopathological diagnosis of osteoblastoma by an incisional biopsy, conservative surgery was performed to remove the lesion. The definitive analysis of the excised tumor confirmed the preoperative diagnosis. The patient has been followed up for a period of 5 years without relapses of the neoplasia. Therefore, due to the rarity and the difficult diagnosis, describing cases like this one and their presentation characteristics is extremely important to enhance knowledge of this pathology among professionals in the area of diagnosis and maxillofacial surgery.

Keywords: Osteoblastoma; Diagnosis, Oral; Maxilla.

 

INTRODUCTION

Osteoblastoma is a rare benign bone tumor that accounts for less than 1% of all primary bone tumors. It most commonly affects young adults, with a mean age of 20 years, usually occurring in long bones and vertebral column. Only 10 to 20% of osteoblastoma occur in the maxillary region, representing approximately 0.7% of the bone neoplasms of this region1-3.

According to the clinical history and histological aspects, there are two well-defined types of osteoblastoma, named a conventional or benign osteoblastoma that presents with slow growth and evolution time of years, well defined sclerotic margin, sparse vascularization, and medial inflammatory infiltration. The other form is known as aggressive osteoblastoma, which is fast-growing, locally invasive, with a propensity to recur, and has atypical histopathological features, often hindering differentiation from low-grade osteosarcoma4,5.

The most common presentation of the benign osteoblastoma involves a swelling with expansion of the bone cortex and slight pain, its size typically do not exceed 4 cm6,7.

The radiographic aspect of the osteoblastoma is not very consistent and varies depending the duration. Generally, it consists in an image with radiopaque and radiolucent patterns, depending on the degree of calcification. In most cases, it´s not possible to identify a perilesional sclerotic border7.

The differential diagnosis of this lesion must include osteoid osteoma, cementoblastoma e fibroma ossificante. Sometimes, the difficult in the diagnostic persists even in the histopathologic analysis, which can resemble other bone-producing lesions, fibrous bone lesions and also osteosarcoma in some cases8,9.

A conservative approach with surgical excision and curettage have been suggested in literature. The recurrence is rare and have been attributable to an incomplete excision9.

Due to the low occurrence and varied histopathological aspects, this pathology becomes a diagnostic challenge. Therefore, our objective of reporting a case of osteoblastoma in the maxilla is to discuss another presentation of this tumor.


CASE REPORT

A 50-year-old male patient, who suffered from leucoderma, presented with the complaint of lack of adaptation of his superior total prosthesis to the ridge, for approximately 2 years, in addition to a complaint of pain if trying to use it. At the extraoral physical examination, the patient presented with facial asymmetry owing to the increase of volume in right zygomatic region with nasolabial groove erasure. In oroscopy, presented with a large expansion in right superior vestibular groove, measuring approximately 4.5 cm on its largest axis, consistent and sore to palpation. The mucosa of the region showed normal and preserved staining.

In computed tomography, we observed an extensive osteolytic lesion in the right maxilla, of solid content, extending laterally up to the zygomatic bone, medially to the nasal fossa, and posteriorly to the tuber region (Figure 1).


Figure 1. Computed tomography, coronal and axial scan, window for soft and hard tissues, showing extensive osteolytic lesion in the right maxilla, with solid content, extending laterally up to the zygomatic bone, medially to the nasal fossa, and posteriorly to the tuber region.



Due to the clinical picture and the tomographic aspect, an incisional biopsy was performed having as diagnostic hypotheses to be clarified an odontogenic tumor and a central ossifying fibroma. In this first procedure, we obtained as the histopathological result a fibrous dysplasia. However, as the images were not compatible with this pathology, we submitted the piece for a new evaluation, this time in the Department of Oral Pathology of FOUSP. This new exam showed an anatomopathological diagnosis of osteoblastoma.

In view of this diagnosis, conservative surgical removal and curettage of the tumor were performed (Figure 2). The excised tumor was submitted to a definitive anatomopathological diagnosis. The histological sections showed fragments of benign bone neoplasia, characterized by the presence of osteoid tissue and bony trabeculae immersed in a richly cellularized and vascularized dense connective tissue stroma, showing spindle fibroblasts. The numerous bony trabeculae that composed the lesion are surrounded by broad osteoblasts which present oval and basaloid nuclei besides abundant eosinophilic cytoplasm. Different degrees of mineralization are verified in the trabeculae and osteoid formations. Within the bony trabeculae, cells with large nuclei are observed and were diagnosed as benign osteoblastoma (Figures 3 and 4).


Figure 2. (A) Expansive increase of volume in right maxilla. (B) Intraoperative aspect of the lesion. (C) Surgical cavity after complete tumor removal. (D) Excised tumor.


Figure 3. Photomicrograph 10X (H&E): osteoid tissue and bony trabeculae with different degrees of mineralization immersed in a richly cellularized and vascularized dense connective tissue stroma, showing spindle fibroblasts. Into the bony trabeculae, cells with large nuclei are observed.


Figure 4. Photomicrography 10X (H&E): (A) Dense connective tissue, richly cellularized. (B) Bony trabeculae, showing cells inside.



The patient has been in a clinical radiographic control for five years without signs of relapse.


DISCUSSION

Although osteoblastoma could affect any bone in the human skeleton, it usually develops in long bones followed by the cervical spine (47-69%). Only about 10% of cases occur in maxillo-mandibular complex, with an apparent predilection for jaw1. In 2006, Jones et al.10 reviewed 77 cases of osteoblastoma and observed that only 28.6% of cases occur in maxilla. It usually occurs in young adults, with the mean age of 20 years6, so our case is unusual because of its location of development and age of diagnostic.

Clinical presentation of this pathology is quite varied. Pain, often mild and longstanding, is the most present symptom11. In the case reported here, the patient complained of pain only when using his total prosthesis. Regarding the clinical alterations, it is generally presented as an expansion of slightly painful cortical bone to palpation, and limited growth does not exceed four centimeters in diameter, in most cases6,11. This report shows a lesion with slow but continuous growth, assuming dimensions that resulted in asymmetry and facial deformity.

Radiographically, its presentation is quite varied, and there is no pattern. Normally, a mixed pattern of radiopacity/radiolucency can be found, depending on the calcification degrees and duration of the frame, in addition to the absence of perilesional sclerotic border12. Therefore, fibro- osseous lesions and odontogenic tumors can be included in a differential diagnosis. Normally, fibrous dysplasia has a ground glass appearance with poorly discernible borders, diverging from the aspects generally observed in osteoblastoma. In contrast, ossifying fibromas manifest as central radiopaque masses surrounded by a radiolucent rim akin to osteoblastoma, although they have a predilection for jaw and are generally well delimited13,14.

On CT scan, we could observe the absence of well-defined lesional limits, as well as a mixed image aspect, which led us to consider whether it is an odontogenic tumor or central ossifying fibroma. Although we can observe odontogenic tumors with a similar radiographic presentation, such as cementoblastoma, odontoma, and desmoplastic ameloblastoma, anatomopathological features are quite different13.

According to the histopathological features, osteoblastoma has been subdivided into conventional (benign) and aggressive. The term benign osteoblastoma was first proposed by two authors in 1956, Jaffe15 and Lichtenstein16. At that time, they used this term to identify an osteoid matrix forming osteoblastic lesion similar to osteoid osteoma, but with higher growth potential.

Later, in 1972, Dorfman17 included osteoblastoma in a review of malignant transformation of benign bone lesions. In a review of his osteoblastoma cases, he noted that some of them exhibited recurrent behavior and non-specific histologic features that would deserve the name of aggressive osteoblastoma. Since then, the term has been used for clinical patterns of greater aggressiveness and speed, having a higher rate of recurrence after conservative therapies.

Initially, osteoblastoma can be a diagnostic challenge. Due to the low incidence in the population, its clinical and anatomopathological standards are often confused with fibro-osseous lesions or odontogenic tumors7. This difficulty was found in our case, in which, at first, we received the provisional microscopic diagnosis of fibrous dysplasia, and only after a slide review, at a reference center in oral pathology, we obtained the description for osteoblastoma.

Osteoblastoma can be included in the microscopic differential diagnosis of fibro-osseous lesions, such as fibrous dysplasia, by the possibility of observing certain similar patterns in these pathologies18 and also of osteoid osteoma, which can be distinguished only by adding the clinical characteristics19. The literature shows that the central feature to distinguish osteoblastoma from other fibro-osseous lesions is that the stroma does not consist of cellular spindle cells but rather is a loose vascular stroma with numerous prominent epithelioid-type osteoblasts18.

In the case presented by us, the lesion was treated conservatively, by means of excision and curettage. In the literature, the therapeutic modality employed ranged from more conservative20 to more aggressive excision in the block, such as maxillectomies or mandibulectomies6,11,13. The most aggressive treatment, with a safety margin, has been indicated in order to reduce recurrence. However, in 2001, Gordon et al. 21 described the likelihood of recurrence for conventional lesions around 13.6%.

However, recurrences of the lesions, when described in the literature, were related to the difficulty of access, facilitating incomplete approaches22,23 or even inadequate initial treatment due to incorrect preoperative diagnosis11. Therefore, the possibility of recurrence would be more related to these factors than to the pathological behavior of osteoblastoma.

Therefore, due to the rarity and the difficult diagnosis, describing cases like this one and their presentation characteristics is extremely important to enhance knowledge of this pathology among professionals in the area of diagnosis and maxillofacial surgery. In our case, the correct diagnosis was only possible when a maxillofacial pathologist was consulted, highlighting the importance of such professional.


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