Fung, WT

Peh, WCG

HKU Scholars Hub

Title Radiological conference. Frontal sinus osteoma complicated bypneumocephalusAuthor(s) Fung, WT; Peh, WCGCitation Hong Kong Practitioner, 1996, v. 18 n. 12, p. 658-662Issued Date 1996URL http://hdl.handle.net/10722/44655Rights Creative Commons: Attribution 3.0 Hong Kong LicenseICEClinical History:A 31-year-old man presented with gradual onset of left frontal headache for one month. Physical examination wasessentially normal. A skull radiograph was requested (Figure 1).Figure 1: Frontal radiograph of the skull1 What is the diagnosis?| a) Paget's disease of skull| b) Fibrous dysplasia (leontiasis ossea)c) Benign hyperostosis of the skull vaultd) Skull fracture causing pneumocephalusI e) Frontal sinus osteoma complicated by pneumocephalusThis radiology case was prepared by:658Dr. W.T. Fung, Medical Officer,Department of Diagnostic Radiology,Queen Mary Hospital.Dr. W.C.G. Peh, Associate Professor,Department of Diagnostic Radiology,The University of Hong Kong.Hong Kong Practitioner 18 (12) December 1996RADIOLOGICAL CONFERENCEAnswer:| e) Frontal sinus; pneumocephalusosteoma complicated byRadiological findingsA dense lobulated mass lesion is seen within theleft frontal sinus, appearances of which are typical of anosteoma. Pneumocephalus is indicated by abnormalintracranial gas lucencies along the midline and over theleft vertex of the cranium (Figure 2). Computedtomography (CT) confirmed the well-defined densenature of the osteoma and its exact extent (Figure 3).Figure 2: Same radiograph as Figure 1. A denselobulated mass typical of an osteoma isseen within the left frontal sinus(arrowheads). Abnormal intracranialgas lucencies are seen along the midlineand over the vertex of the cranium(arrows)Figure 3: Coronal CT of the paranasal sinuses. Theimage is displayed in bone window settingfor better delineation of bony detail. Theosteoma (open arrows) appears as a well-defined bony mass within the left frontalsinus. Pneumocephalus (arrowheads) isalso well demonstratedDiscussion(a) Paget's disease of skullThis condition of excessive bone remodelling isvery rare in patients under 40 years and amongChinese. The skull is affected in 65% of cases.Radiographically, the skull vault is thickened andthere are multiple 'cotton wool' islands of bonydensity.1 None of these features are present in thiscase.(Continued on page 661)659Hong Kong Practitioner 18 (12) December 1996RADIOLOGICAL CONFERENCE(b) Fibrous dysplasia (leontiasis ossea)Leontiasis ossea is a sclerosing form of fibrousdysplasia affecting the facial bones and the skullbase. The rest of the skeleton is rarely affected.1In this case, the site of involvement does not fit thisdiagnosis.(c) Benign hyperostosisThis is commonly seen in post-menopausal women,and rarely affects men. On radiographs, benignhyperostosis is seen as thickening and localizedincreased density of the inner table of the skullvault, giving rise to the so-called "choppy-sea"appearance. It involves mainly the frontal region,in a symmetrical and bilateral manner.1 In thiscase, this diagnosis can be excluded on basis of age,sex and radiological appearance.(d) Skull fractureFractures involving the frontal sinus, other sinusesand the skull vault may give rise to the seriouscomplication of intra-cranial pneumocephalus.There may be a radiographically-detectable air-fluidlevel in the sinuses if the fracture involves thesestructures. In this case, the absence of a traumatichistory and lack of a fracture line at the frontalsinus are against this diagnosis.(e) Frontal sinuspneumocephalusosteoma complicated byOther causes of intra-cranial pneumocephalusinclude previous cranial surgery, intracranialabscess or erosion of the paranasal sinuses bytumour mass or inflammatory process. A relevantclinical history helps in narrowing the differentialdiagnosis. Frontal sinus osteoma is the mostcommon cause of intrasinus ossification, withdevelopment of pneumocephalus being a rare butwell recognized complication.2'3Osteoma is the commonest tumour affecting theparanasal sinuses, occurring in up to about 1% ofindividuals.4 The frontal sinus is most frequentlyaffected, followed by the ethmoid sinus. Involvement ofthe sphenoid and maxillary sinuses is uncommon. Menare more commonly affected than women with a male-to-female ratio of about 3 to I.5 It predominantlyoccurs in the 3rd and 4th decades of life.Two types of osteoma, ivory and cancellous, areidentified. The former is the more common type whichappears as a dense well-defined lobulated mass.Cancellous osteoma has a very low density and istherefore less obvious on plain radiographs. CT isuseful for confirming the presence and defining theexact extent of osteoma, particularly of the cancelloustype. Multiple sinus osteomata are seen in Gardner'ssyndrome, which also manifests with colonic polyps,basal cell naevi and epidermoid cysts of the skin.3-4The majority of osteomata are asymptomatic. Theyare usually detected incidentally during radiographicexamination of the skull or sinuses for other unrelatedcauses. Symptomatic osteomata may present with facialpain, sinus infection or headache. Obstruction to thesinuses by the osteoma may lead to complications suchas secondary mucocele formation or proptosis. Bonyerosion of the sinus wall and encroachment of orbit andcranium may occur with large tumours, causing leakageof cerebrospinal fluid, meningitis and brain abscess. Asin our case, pneumocephalus results from erosion of thefloor of the anterior cranial fossa by a frontal sinusosteoma.3-5Surgery is usually required for patients who havesymptoms or complications related to the osteoma. Forasymptomatic osteomata, some controversy existsregarding their management. In general, regular plainradiographs every 1 to 2 years are recommended for thefollow-up of small asymptomatic osteomata that arelocated away from the sinus osteum.6 Patients shouldbe advised to return for early reassessment shouldsymptoms arise. Early surgical removal is suggested forlarge tumours, and for those that are located near thenasofrontal duct.5 •661Radiological ConferenceRADIOLOGICAL CONFERENCEReferences1. Chapman S, Nakielny R. Aids to Radiological Differential Diagnosis.3rd ed. Bailliere Tindall, London. 1995; 384-385.2. Zizmor J, Noyek AM. Radiology of the nose and paranasal sinuses.In: Paparella MM, Shumrick DA(eds). Otolaryngology. 2nd ed. W.B.Saunders Co, Philadelphia. 1980; 1016-1066.3. Lloyd GAS. Osteogenic tumours. In: Lloyd GAS. Diagnostic Imagingof the Nose and Paranasal Sinuses. Springer-Verlag, Heidelberg.1988: 167-173.Powell T, Jenkins JPR. Ear, nose and throat. Head and neck radiology.In: Grainger RG, Allison DJ (eds). Diagnostic radiology. An Anglo-American textbook of imaging. 2nd ed. C h u r c h i l l Livingstone.Edinburgh. 1992; 2121-2163.Rappaport JM, Attia EL. Pneumocephalus in frontal sinus osteoma: Acase report. J Otolaryngol 1994; 23: 430-435.Weymuller, EA. Neoplasms. In: Cummings CW. (ed.).Otolaryngology - Head and Neck Surgery. CV Mosby, St. Louis.1986; 923-936.C O N F E R E NPlease reserve' your;; Place';:Scientific Subcommittee^ ..... ;;;;662

Radiological conference. Frontal sinus osteoma complicated by pneumocephalus

http://hub.hku.hk/bitstream/10722/44655/1/24871.pdf

Radiological conference. Frontal sinus osteoma complicated by pneumocephalus

Abstract

Similar works

Full text

Available Versions

HKU Scholars Hub