Sinonasal Ossifying Fibroma: A Study of Six Cases and Review of Literature
B Vikram, S Udayashankar
cementifying fibroma, jaw neoplasm, ossifying fibroma, paranasal sinus neoplasm
B Vikram, S Udayashankar. Sinonasal Ossifying Fibroma: A Study of Six Cases and Review of Literature. The Internet Journal of Otorhinolaryngology. 2005 Volume 4 Number 2.
Diagnostic dilemma of ossifying fibroma can be overcome with a combination of clinical, radiological and pathological criteria.
It is preferable to remove the tumor enmass, take multiple sections for histopathological reporting to avoid missing the subtypes.
Complete surgical excision of the tumor is possible when surgery is based on preplanned criteria.
Ossifying fibroma is a destructive, deforming, slow growing, benign fibro-osseous tumor that can occur almost anywhere in the facial skeleton. This uncommon tumor can present a diagnostic dilemma for the clinician and the pathologist, owing to overlapping clinical and histomorphologic features. Many synonymous nomenclatures exist for a single entity and the controversy in classification and staging of the subtypes in the literature has added to the confusion. Hence there is a need to highlight the points of controversy existing for this tumor so that they could be avoided through a consensus in future. The tumor can produce sinus obstruction, infection, facial deformity, proptosis and intracranial complications, even though it can remain asymptomatic in the early stage. Therefore the tumor needs to be excised completely in order to prevent recurrence. Complete excision is dependent on the correct surgical approach. Hence we decided to base our surgeries on preplanned criteria to excise the tumor completely and minimize recurrence. This paper has been presented with the following objectives:
To present 6 cases of ossifying fibroma that were successfully treated by different surgical approaches by us
To compare the clinical profiles of various types of ossifying fibroma and discuss the controversies those exist for this tumor in literature.
To discuss the diagnostic dilemma associated with ossifying fibroma
To discuss the various surgical approaches to this uncommon tumor in the sinonasal region.
Materials And Methods
This is a prospective descriptive study of all cases of sinonasal ossifying fibroma that were diagnosed and treated in a period of 2 years in a medical college referral hospital catering to both urban and rural population. Cases from all ages and both sexes were included. Cases with tumor involving the orbit and the cranial cavity were also included. But those cases with the tumor involving the lower jaw, recurrences of tumor and other conditions like fibrous dysplasia were excluded. The diagnostic details of the patients are described in table 1.
Investigations such as X-ray paranasal sinuses [PNS], CT scan PNS (Fig 1 to 3), diagnostic nasal endoscopy (Fig 4) and biopsy were performed on all the patients. The classical
We decided to plan our surgeries based on the following criteria:
To perform the least radical tumor resection possible
To excise the tumor in toto and also try to remove it enmass wherever possible.
To cause least damage to the surrounding structures that might affect the growth of the craniofacial skeleton
To try to avoid an external scar, especially in pediatric patients
To try to prevent recurrence of tumor
The type of approach was decided by the following factors:
Age of the patient
Presence of complications
Histopathological type of tumor
Surgical criteria already mentioned
A Medline literature search with key words
Six cases of craniofacial ossifying fibroma were surgically treated by various surgical approaches. All the 6 patients were operated under general anesthesia. Details of the surgeries are given in table 2. The photograph of the tumor mass that was excised in case 2 is shown in figure 5. In case 4, a dual approach had to be employed due to the significant intracranial extension of the tumor. The help of a neurosurgeon was taken to excise the intracranial portion of the tumor by a bifrontal craniotomy. The CSF leak was sealed and the dura was repaired with fascia lata. The nasal part of the tumor was removed piecemeal by rigid nasal endoscopy in the same sitting. Intraoperative bleeding was moderate in all cases except in case 5 where blood transfusion had to be given. The excised mass in all cases was sent for histopathological examination. An endoscopic assessment of the surgical cavity after tumor excision was done in every case. No recurrence was observed clinically, endoscopically and radiologically in any of the cases in a follow up period of one year.
Thirty papers related to the diagnostic and treatment aspects of ossifying fibroma were studied after the Medline search. Eight papers were found to be associated with some or the other controversy. A detailed discussion of the diagnostic difficulties and controversies associated with ossifying fibroma has been made in the discussion part of this paper.
Ossifying fibroma is a relatively uncommon benign fibro-osseous tumor commonly affecting the craniofacial region. The neoplasm closely resembles the non-neoplastic condition fibrous dysplasia in many respects especially in histology. Hence many pathologists still consider it to be a variant of fibrous dysplasia. The classification of ossifying fibroma with many synonymous nomenclatures has been a matter of controversy. The various names associated with ossifying fibroma are
Interestingly, some authors have suggested that all the fibro-osseous lesions relating to ossifying fibroma and its subtypes should be referred to as ossifying fibroma only since they claim that there is no difference in behavior between the subtypes and the histological designations are only academic.14
Even though some authors opine that fibrous dysplasia and ossifying fibroma cannot be distinguished by microscopy due to histological overlap3,6 others opine that there are many features like the absence of cementicles, lamellar trabeculae and osteoblasts to distinguish them.1 The differentiation between the 2 entities is of great importance because of their divergent clinical behavior. Fibrous dysplasia is often polyostotic whereas ossifying fibroma is usually monostotic.17 Fibrous dysplasia is usually a self-limiting disease and therefore a complete resection is unnecessary and in most instances impossible.18 Radiographically ossifying fibromas are classically described as circumscribed unilocular lesions with a surrounding rim of eggshell thin bone giving a
The overall prognosis with most types of ossifying fibroma appears to be good. Despite their tendency for local invasion and recurrence, there are no reported instances of metastatic disease with the exception of certain subtypes of ossifying fibromyxoid tumor. The development of aneurysmal bone cyst in psammomatoid ossifying fibroma has been reported.6 Malignant transformation is very rare.2 Meningitis secondary to invasion into the cranial cavity has been reported and rarely even death may occur.23 Surgery is the mainstay of treatment for all types of ossifying fibroma. Growth of the facial skeleton is an important consideration in the pediatric age group.24 Extensive tumors in this age group are more difficult to manage since the tumors here tend to be more invasive, aggressive and have more chances of recurrence. Mandibular tumors can be treated with conservative surgery but aggressive surgery is warranted for midface and paranasal sinuses because of their more aggressive behavior.2 Even though small tumors can be removed by simple curettage and enucleation, they are better avoided for the fear of recurrence especially in juvenile ossifying fibroma. One study showed a recurrence rate of 28% after curettage.14 Endoscopic removal has also been tried successfully.28 But these conservative techniques and piecemeal approaches could make histological interpretation more difficult, especially in cases of hybrid lesions. Hence wherever possible, an open surgical technique is advised for adequate visualization and complete excision.8 Various radical and semi radical resection procedures have been tried. Fronto-parietal craniotomy with cranioplasty has been done for lesions of the parietal bone.5 Similarly partial mandibulectomy followed by plate fixation has been done for mandibular lesions.5 Extensive bilateral tumors require combined multiple approaches whereby the tumor is excised portion by portion. Bilateral nasal tumors have been removed by modified lateral rhinotomy with bilateral ethmoidectomy and sphenoidotomy.9 Larger lesions with intracranial extension may require enbloc resection or craniofacial resection.25,26
Surgical complications may include significant blood loss, requiring transfusion and loss of vision.23,27Recurrences after surgery have been common and reported to be in the range of 30 to 56%.23Treatment of recurrences by revision surgery is difficult again in the pediatric group. Radiotherapy has been proven to be ineffective and is contraindicated due to an increased incidence of malignant transformation ranging from 0.4 to 44%9 with the exception of certain subtypes of ossifying fibromyxoid tumor.
In our experience, the Lynch Howarth approach has been particularly useful to relieve proptosis when the tumor was confined only to the medial portion of the orbit and the ethmoid. The extended Caldwell Luc approach and sublabial approach are more suitable for lesions involving the maxilla and the premaxilla and had the advantage of having no external scar. Lateral rhinotomy approach gave the widest access and exposure to all the regions, but with an external scar. Nasal endoscopic excision had the advantage of tumor excision under direct vision and had no external scar. Hence it could be used as adjuvant for other approaches especially when the tumor was extensive and had to be removed piecemeal. It was also useful to assess the surgical cavity for bleeding and tumor remnants after the excision of the tumor by any approach. But it had the disadvantage of piecemeal removal, risk of recurrence and excessive time consumption for the procedure especially if it was the sole approach employed for removal of the tumor. Hence it appeared to be more suitable for early tumors especially in the pediatric patients where radical surgeries were not advisable. Craniotomy approach had the maximum hospital stay due to higher morbidity.
This study has highlighted the versatile presentation and the heterogeneous nature of this benign tumor in the sinonasal region. Larger comparative studies of longer duration and follow up might be required to suggest an algorithm that could be useful in the decision making process for this tumor. But since the tumor is uncommon, it is difficult to undertake such prospective studies in a reasonable period of time.
Ossifying fibroma is a benign fibro-osseous tumor of the craniofacial region that is diagnosed with a combination of clinical, radiological and pathological criteria. Due to the possibility of the presence of hybrid lesions in this tumor, it is preferable to remove it enmass and take multiple sections for histopathological reporting. This would avoid missing a particular subtype of the tumor that might need a different surgical management. The classification of the subtypes and the nomenclature of this tumor have remained controversial. There is a need for consensus regarding the nomenclature and classification of this tumor. The surgical approaches and techniques have also not been well defined especially in the young patients. Complete surgical excision of the tumor is possible when surgery is based on preplanned criteria. Six cases of different types of sinonasal ossifying fibroma managed successfully by various surgical approaches have been presented.
The authors would kindly like to acknowledge the support given by the Department of pathology, KIMS, Hubli in reviewing the histopathology slides, discussing them and providing the photographs to us.
Dr.Vikram Bhat K MS, DNB, MNAMS (ORL – HNS) No: 4-64, Sagri Nole, Kunjibettu Post, Udupi – 576102, Karnataka, India Tel (Res): +918362370579 Cell: +919448658213 Email: firstname.lastname@example.org