Tomographic features of craniofacial fibrous dysplasia: a retrospective study of 14 cases

Abstracts

OBJETIVO: Apresentar as várias formas de displasia fibrosa craniofacial em um estudo revisional com 14 exames de tomografia computadorizada. MATERIAIS E MÉTODOS: Foram selecionados 14 casos de displasia fibrosa craniofacial atendidos no Serviço de Cirurgia de Cabeça e Pescoço e Otorrinolaringologia e no Serviço de Diagnóstico por Imagem do Hospital Heliópolis, São Paulo, SP, entre 1991 e 2002. Foram avaliados, pelos autores, três dos achados tomográficos mais relevantes: o número de ossos acometidos, a apresentação radiológica predominante e a uni/bilateralidade da doença no crânio. RESULTADOS: Observou-se predomínio do padrão misto em relação à forma de apresentação da doença. Foram vistos, ainda, acometimento contíguo de dois ou mais ossos e equivalência entre casos de acometimento craniofacial unilateral e bilateral, possivelmente por conta dos pacientes serem, em sua maioria, portadores de displasia fibrosa do tipo monostótica. CONCLUSÃO: O conhecimento das características tomográficas da displasia fibrosa craniofacial é de grande importância para que seja feito planejamento cirúrgico adequado e seguimento pós-tratamento.

Displasia fibrosa óssea; Crânio; Face; Ossos faciais; Tomografia computadorizada por raios X

ORIGINAL ARTICLE

Tomographic features of craniofacial fibrous dysplasia: a retrospective study of 14 cases^*

Renato Assayag Botelho^I; Olger de Souza Tornin^I; Ilka Yamashiro^II; Marcelo Carneiro Menezes^I; Sérgio Furlan^III; Maurício Ridelenski^IV; Rubens Yamashiro^V; José Francisco Sales Chagas^VI; Ricardo Pires de Souza^VII

^IMD, Radiologists, Master Degree students in Sciences of Health at Hospital Heliópolis

^IIMD, Radiologist, Master in Sciences of Health at Hospital Heliópolis

^IIIMD, Radiologist

^IVMD, Radiologist, Doctorate student in Radiology at Universidade de São Paulo

^VMD, Radiologist, Chief at Hospital Heliópolis Computed Tomography Sector

^VIProfessor of Course of Post-Graduation at Hospital Heliópolis, Doctor in Medicine by Universidade Federal de São Paulo-Escola Paulista de Medicina

^VIICoordinator of Medical Residency in Radiology and Diagnostic Imaging at Hospital Heliópolis, Professor of Course of Post-Graduation at Hospital Heliópolis, Doctor in Radiology by Universidade de São Paulo

^{Mailing Address}

ABSTRACT

OBJECTIVE: To describe the different presentations of craniofacial fibrous dysplasia in a revisional study of 14 computed tomography exams.

MATERIALS AND METHODS: The authors have selected 14 cases of craniofacial fibrous dysplasia attended at the Head & Neck Surgery/Otorhinolaryngology Service and Diagnostic Imaging Service of "Hospital Heliópolis", São Paulo, SP, Brazil, between 1991 and 2002. Three of the following most relevant tomographic findings were analyzed: number of bones affected, predominant radiological presentation and the disease uni- or bilaterality.

RESULTS: A predominance of a mixed pattern was observed in relation to the disease presentation. Also, contiguous involvement of two or more bones was observed as well as equivalence between cases of unilateral and bilateral craniofacial involvement, possibly due the fact that most patients presented the monostotic type of fibrous dysplasia.

CONCLUSION: The knowledge of tomographic features of craniofacial fibrous dysplasia is of paramount importance for surgical planning and post-treatment follow-up.

Keywords: Fibrous dysplasia of bone; Skull; Face; Facial bones; X-ray computed tomography.

INTRODUCTION

Fibrous dysplasia is a benign developmental anomaly of the bone-forming mesenchyme where the medullary bone is replaced by fibrous tissue, woven bone and spindle cells⁽¹⁾. Most frequently this disease is observed in the first three decades of life^(2,3). Although the fibrous dysplasia is a disease of benign nature, there are reports on malign transformation associated with this disease presentation^(4,5).

The craniofacial region is an important site affected, most commonly including maxilla and mandible^(6–8). The involvement of facial bones may cause noticeable thickening and sclerosis, frequently with obliteration of sinuses and orbits, creating a "leonine" appearance (leontiasis ossium)⁽⁹⁾. Other conditions associated with fibrous dysplasia in this region are craniofacial deformities, malocclusion and visual acuity decrease (this latest, with absolute surgical indication).

Amongst the imaging methods, computed tomography has been the method most frequently employed to demonstrate extent and radiodensity of the fibrous dysplasia in craniofacial bones, and therefore is of paramount importance for the surgical planning and post-surgical longitudinal follow-up of patients^(10,11). Fibrous dysplasia tomographic findings may vary considerably, depending on the amount of osseous tissue present in the lesion. Apparently, patterns of affection may be classified into: sclerotic, cystic or mixed⁽¹²⁾.

In skeleton, the most commonly found pattern is the mixed one^(6,13). This pattern is characterized by an association of sclerotic and cystic areas⁽¹⁰⁾ (Figures 1 and 2). The cystic pattern presents sclerotic margins and an ovoid or doughnut configuration⁽⁶⁾ (Figures 3 and 4) and the sclerotic pattern is frequent in younger patients, radiographically consisting of ground-glass opacities and osseous expansion (Figures 5 and 6).

The present study seeks to demonstrate the tomographic aspects of the main fibrous dysplasia presentations by means of an analysis of 14 craniofacial CT studies of patients firmly diagnosed with craniofacial fibrous dysplasia, comparing them with the findings reported in the medical literature.

MATERIALS AND METHODS

In the period between 1991 and 2002, 14 skull and face CT studies of patients firmly diagnosed with craniofacial fibrous dysplasia were retrospectively selected. From 14 patients, seven were male (50%) and seven female (50%), with ages ranging between 8 and 33 years. Studies were performed in third generation CT equipment, with acquisition of axial and coronal slices. Slice thickness and table increment were 3 mm and 5 mm, respectively.

Inclusion criteria for this study were: patients should be treated at Hospital Heliópolis Service of Head & Neck Surgery, should present anatomopathological confirmation and no previous treatment or any interventional procedure before acquisition of CT images. During the selection process, studies performed after surgical intervention and patients who presented with cherubism (a hereditary form of fibrous dysplasia).

The cases were evaluated by two radiologists who are titular members of Colégio Brasileiro de Radiologia e Diagnóstico por Imagem (Brazilian College of Radiology and Diagnostic Imaging). By means of the studies reading, they have analyzed findings like number of bones affected, predominating radiological presentation (the answer should be: sclerotic, cystic or mixed pattern) and disease uni- or bilaterality.

RESULTS

The results obtained after evaluation by both radiologists are included in Tables 1, 2 and 3.

DISCUSSION

Fibrous dysplasia also may be divided into two groups as regards its forms of presentation: monostotic and polyostotic.

The monostotic form is that where a single bone or contiguous bones are affected⁽¹⁰⁾. It is considered the most common form of the disease, corresponding to about 70% of cases⁽¹⁰⁾. Children and young adults are more frequently affected, the incidence being equal in males and females⁽⁶⁾. Most of times, the lesions stop developing with the growth plate closure⁽¹⁴⁾. Clinically, the disease is characterized by expansion of the area involved of bone, with saliences of the osseous laminae.

The polyostotic form by its turn occurs in two or more non-contiguous bones. Approximately 30% of fibrous dysplasias are polyostotic. Age ranges affected are similar to those of the monostotic form, with a female predominance. Clinical manifestations usually occur in the childhood and initially are insidious and may course with bone pain. In cases where this form of dysplasia is associated with pigmented macules or cafe-au-lait spots on skin and endocrinopathy, the disease is called McCune-Albright syndrome⁽¹⁴⁾. Almost all patients with polyostotic fibrous dysplasia present craniofacial involvement, with an astonishing prevalence in one side of the body^(8,10). However, most of patients presenting the disease in craniofacial bones have the monostotic form⁽¹⁰⁾.

In the sample studied, the majority of patients developed monostotic fibrous dysplasia. So, the findings of contiguous compromising in the presence of the disease in two or more bones and the equivalence between cases of uni- and bilateral craniofacial involvement are compatible with results of studies published in the medical literature^(10,12,15). Similarly to these studies, we have also found the mixed pattern as the predominant tomographic pattern.

CONCLUSION

The knowledge of the several craniofacial fibrous dysplasia tomographic aspects is of paramount importance for the general radiologist, since the imaging findings, in this disease, are quite typical and CT plays a fundamental hole in the surgical planning and the patient's follow-up.

REFERENCES

Received November 21, 2005.

Accepted after revision November 30, 2005.

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*

Study developed at Hospital Heliópolis Diagnostic Imaging Service, São Paulo, SP, Brazil.

Publication Dates

• Publication in this collection
  26 Sept 2006
• Date of issue
  Aug 2006

History

• Accepted
  30 Nov 2005
• Received
  21 Nov 2005