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Atypical simple bone cysts of the jaws. I: Recurrent lesions
Clinical Radiology (1988)39, 53-57
Atypical Simple Bone Cysts of the Jaws. I: Recurrent Lesions K. H O R N E R , G. H. FORMAN* and N. J. D. SMITH Departments of Dental Radiology and * Oral & Maxillofacial Surgery, The Dental School, King's College School of Medicine and Dentistry, Denmark Hill, London SE5 8 R X The aetiology, clinical and radiographic features and the treatment of simple bone cysts of the jaws are discussed. Recurrence of jaw lesions is unusual. Two cases are presented of simple bone cyst in the mandible which recurred following conventional treatment. The importance of clinical and radiographic follow-up is emphasised.
The simple bone cyst is a pathological cavity lying within bone and lacking any epithelial lining, arising most commonly in the proximal ends of the humerus and femur. A lesion with the same name and features is found in the jaws and is generally considered the same entity (Lucas, 1984). Although Campanacci et al. (1986), who surveyed the skeletal distribution of simple bone cysts, described lesions other than in the humerus and femur as 'definitely rare', they did not include any cases arising in the jaws. Such lesions are not so uncommon as once thought, but do not usually come to the attention of general radiologists and orthopaedic surgeons who are acquainted with the cyst elsewhere in the skeleton. Various names have been coined for the simple bone cyst supposedly to reflect its putative aetiology or appearance (e.g. traumatic, solitary, unicameral, haemorrhagic and extravasation bone cyst) but the term simple bone cyst is preferred here as the most noncommittal. Despite numerous theories, the aetiology of simple bone cysts remains obscure and no individual theory explains all the circumstances in which the lesions are found. M6nckeberg (1904) proposed that bone cysts were healing giant cell tumours or osteitis fibrosa. A relationship to giant cell tumours was further suggested by Rushton (1946), with some circumstantial support subsequently reported by Huebner and Turlington (1971) and Hillerup and Hjorting-Hansen (1978). Apart from this there are two important theories of possible aetiologies: one supports a haemorrhagic cause, the other a developmental origin. The haemorrhagic theory depends upon the formation of an intra-medullary haematoma following either arterial (Pommer, 1920) or venous (Olech et al., 1951) bleeding within bone. This possibly could occur following trauma which is either too slight, or of a type (e.g. compressive, torsional) insufficient to cause a fracture. Instead of undergoing normal organisation and healing it is suggested that such a haematoma might lyse and the involved bone resorb, to leave a bony 'space'. Subsequently, perhaps involving factors such as poor venous drainage (Cohen, 1970) and a high intracystic hydrostatic pressure (Chigira etal., 1983), this could develop into the bone cavity recognised as a simple bone cyst. The jaws are a frequent site of trauma, and there has been much discussion on its relationship to cyst development in the literature. However, the objective recording of a history of trauma is difficult, and such disparate figures of between 26.9% (Beasley, 1976) and 81% (Hansen et
al., 1974) of patients giving such a history underlines that the traumatic theory of origin is not proven. Jaffd (1953) first postulated that the simple bone cyst was a developmental 'aberration'. Hosseini (1978), suggested that it could arise in development by metaplasia of osteogenic into synovial cells, as produced experimentally by Trueta (1968), forming multiple synovial cavities which coalesce to form a fluid-containing cyst. There is support for this in the work of both Johnson and Kindred (1958), who reported a resemblance between synovial bursae and cyst linings, and Mirra et al., (1978) who claimed to find 'unmistakable' synovial cells in the walls of the simple bone cyst of the femur. Such a theory is in accordance with the sites of predilection of the lesion close to the synovial-capsular-bone reflection in the long bones, but fails to explain why the temporomandibular joint is a rare site of occurrence for jaw lesions. It is suggested that the latter anomaly is related to the unusual growth pattern of the mandible, permitting translocation of potential lesions into the toothbearing regions (Hosseini 1978). Jaw lesions are usually fortuitous discoveries on routine dental radiographs, between 60 and 80% of patients being quite asymptomatic (Howe, 1965; Beasley, 1976). When symptoms occur, the commonest are swelling and pain (Huebner and Turlington, 1971). With mandibular lesions, disturbed labial sensation (De Tomasi and Hann, 1985) and pathological fracture (Cowan, 1980) have been reported as rare presenting signs. As with long bone lesions, most cysts arise in children with a peak incidence in the second decade (Howe, 1965; Huebner and Turlington, 1971). There is a small but consistent predilection for the development of cysts in males (Howe, 1965; Kuroi, 1980). It is unusual for cysts to arise outside the tooth-bearing parts of the jaws, thus corresponding to the sites of haemopoietic bone marrow (Howe, 1965). However, isolated cases have arisen in the mandibular condyle (Gilman and Dingman, 1982; Persson, 1985). Lesions are more common in the mandible than in the maxilla, the latter constituting between 11% (Kuroi, 1980) and 32% (Hansen et al., 1974) of the total of jaw lesions. In the mandible the molar regions are favoured sites while in the maxilla the intercanine region is usually affected. Expansion occurs in a minority of cases, but when present is usually bucco-labial (Howe, 1965). Associated teeth maintain normal vitality and are rarely displaced by the lesion (Huebner and Turlington, 1971). Radiologically the classic appearance of the simple bone cyst is a well-defined radiolucency with a very characteristic 'scalloped' appearance where it extends between the roots of the teeth (Lucas, 1984). However, the appearance commonly departs from these 'typical' features, and Hansen et al. (1974) concluded that the size, shape, margins and degree of radiolucency were quite variable. Thus simple bone cysts have been misdiagnosed prior to surgery as dentigerous cysts (Sharma, 1983), radicular cysts (Winer and Doku, 1978) and
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CLINICAL RADIOLOGY
r e s i d u a l cysts ( C o h e n , 1984). L e s i o n s a r e u s u a l l y single b u t o c c a s i o n a l l y m u l t i p l e ( H e i m d a h l , 1978; R a i b l e y et al., 1979), a n d g r e a t size m a y b e a t t a i n e d b e f o r e d e t e c tion ( F r e e d m a n a n d B e i g l e m a n , 1985). M u l t i l o c u l a r i t y is an o c c a s i o n a l f i n d i n g ( N a r a n g , 1980; M i t c h e l l a n d W a r d - B o o t h , 1984) a n d it is this m o r e t h a n a n y o t h e r f a c t o r which m a y c o n f u s e d i f f e r e n t i a l d i a g n o s i s a n d suggest an aggressive l e s i o n such as a m e l o b l a s t o m a , prim o r d i a l cyst or o d o n t o g e n i c m y x o m a . H o w e v e r , t h e l a m i n a d u r a a r o u n d a s s o c i a t e d t e e t h r e m a i n s intact ( C h a p m a n a n d R o m a n i u k , 1985) a n d r o o t r e s o r p t i o n is an e x t r e m e l y r a r e f i n d i n g ( D a r a m o l a et al., 1978). S u r g e r y r e m a i n s t h e first c h o i c e o f t r e a t m e n t for simple b o n e cysts of t h e j a w s , n o t least b e c a u s e d e f i n i t i v e diagnosis can o n l y b e m a d e a f t e r surgical e x p l o r a t i o n . Surgical access to t h e j a w s is s t r a i g h t f o r w a r d , a n d t h e f o r m a t i o n of a ' w i n d o w ' into the cavity, w i t h c u r e t t a g e of the walls to p r o m o t e b l e e d i n g a n d h a e m a t o m a f o r m a tion, r e a d i l y l e a d s to its r e s o l u t i o n b y b o n y r e g e n e r a tion. Other treatments, such as i n j e c t i o n of m e t h y l p r e d n i s o l o n e a c e t a t e into cysts a n d the use of b o n e grafts a r e n o t c o n v e n t i o n a l p r a c t i c e . A t s u r g e r y , cysts m a y b e e m p t y o r c o n t a i n v a r i a b l e a m o u n t s o f fluid usually d e s c r i b e d as s e r o s a n g u i n o u s , a l t h o u g h w h o l e blood may be encountered (Chapman and Romaniuk, 1985). H o w e (1965) b e l i e v e d ' d r y cavities' r e p r e s e n t o l d e r lesions. T h e e v i d e n c e for s p o n t a n e o u s r e g r e s s i o n o f s i m p l e b o n e cyst is n o t c o m p l e t e l y p r o v e n , as diagnosis of s i m p l e b o n e cyst was m a d e w i t h o u t surgical o r histological e v i d e n c e in t h e cases r e p o r t e d ( B l u m , 1955; Szerlip, 1966). P a t h o l o g i c a l s p e c i m e n s a r e c o m m o n l y little m o r e t h a n a few b o n y f r a g m e n t s . This p a u c i t y of m a t e r i a l r e m a i n s a p r o b l e m in f u r t h e r i n g k n o w l e d g e of t h e p a t h o l o g y o f s i m p l e b o n e cyst. H o w e v e r , it is c l a i m e d by G i l m a n a n d D i n g m a n (1982) t h a t o n careful e x a m i n a tion a lining, a l b e i t s c a n t y , is always f o u n d consisting of c o n n e c t i v e tissue, g r a n u l a t i o n tissue, o s t e o b l a s t s a n d osteoclasts. E x t r a v a s a t e d r e d b l o o d cells a n d h a e m o siderin d e p o s i t s a r e also f o u n d ( B e a s l e y , 1976). E p i thelial cells a r e n e v e r f o u n d o r d e s c r i b e d in t h e r e p o r t s in t h e d e n t a l l i t e r a t u r e . H o w e v e r , in cysts of the f e m u r M i r r a et al. (1978) h a v e r e p o r t e d cells with basal l a m i n a e (i.e. e p i t h e l i a l cells) in t h e c o n n e c t i v e tissue lining i d e n tifiable as s y n o v i a l ' A ' a n d ' B ' cells. N o such s e a r c h has b e e n c a r r i e d o u t for e p i t h e l i a l cells b y o r a l p a t h o l o g i s t s as far as w e k n o w , a n d such r e s e a r c h w o u l d b e of h e l p in the e v a l u a t i o n of t h e s y n o v i a l t h e o r y ( M i r r a et al., 1978; H o s s e i n i , 1978) o f o r i g i n for s i m p l e b o n e cysts. T h e p r o g n o s i s f o l l o w i n g c o n v e n t i o n a l t r e a t m e n t is v e r y g o o d a n d r e c u r r e n c e is r a r e . T h e a v e r a g e t i m e f r o m o p e r a t i o n to c o m p l e t e h e a l i n g has b e e n r e p o r t e d as just o v e r 12 m o n t h s ( H u e b n e r a n d T u r l i n g t o n , 1971).
Fig. 1 - Case 1. Section of dental panoramic tomogram (DPT) taken at initial presentation, demonstrating the radiolucent lesion in the right body of mandible.
A provisional diagnosis of simple bone cyst was made and the patient admitted for surgery. Upon raising a buccal mucoperiosteal flap, only a bluish eggshell-thin layer of bone was present overlying the cavity. On gaining access to the lesion it was found to contain clear fluid but no obvious lining. The cavity was allowed to fill with blood and the wound closed. Healing was uneventful and after 6 months considerable bony regeneration has recurred (Fig. 2). However, after a further year radiographs showed a recurrence, with growth of a new lesion even larger than the original (Fig. 3), extending from the 81 region across the midline as far as ~, with 'scalloping' at the lower border of the mandible. A second, more extensive, operation was performed. Prior to opening the cavity aspiration yielded clear fluid. The lesion was then entered but contained no peripheral lining. However, it was noted that, adjacent to the roots of the teeth, there were a number of separate, intact, fluidcontaining saccules; these burst to release clear fluid on only slight manipulation. The bony window was extended to include the entire buccal wall of the cavity, fragments of the removed bone being retained for histological examination. The wound was closed conventionally. After 10 months there was radiographic evidence of considerable bonyfegeneration; all the previously involved teeth were vital, including 761 which had given non-vital response to careful testing at the time of the original lesion.
CASE REPORTS Case 1. A 13-year-old girl was referred by her general dental practitioner with regard to a radiolucent 'cystic' area observed radiographically in the right side of her mandible. The patient was symptomless. On examination a slight intra-oral swelling was observed buccal to the lower right molar teeth. 7~ gave a non-vital response to electric pulp testing despite being caries-free. Radiographs revealed a large radiolucency in the right mandible which extended superiorly between the roots of 7654] and showed some thinning of the cortical plate at the lower border of the mandible in relation to the lesion (Fig. 1). Faint bony septae were visible running almost verticallyfrom the apices of 654] to the lower wall of the defect.
Fig. 2 - Case 1. At 6 months after surgery the site of the lesion shows a large degree of bony regeneration.
CYSTS OF THE JAWS
55
supporting the clinical appearance of a simple bone cyst. Healing proceeded well, and after 6 m o n t h s m u c h bone had formed in the site of the lesion (Fig. 5). However, 3 years after surgery radiography demonstrated recurrence of the radiolucency in the origin~/l site (Fig. 6). After a further 18 m o n t h s of observation the new lesion had increased in size (Fig. 7) and further surgery was considered to be necessary. This was carried out following the same procedure as previously. At surgery, following aspiration of 5 ml of 'red fluid' the lesion was opened to reveal a rough-walled cavity without a lining. Closure of the wound was then effected. Protein electrophoresis of cyst fluid showed a normal s e r u m pattern, and histology of the wall of the lesion demonstrated a lining of fibrous connective tissue with m a n y osteoblasts and osteoclasts. Therefore, once again the histology confirmed the clinical diagnosis of simple bone cyst.
Fig. 3 - Case 1. A n e w radiolucent lesion is present extending across the mid-line 18 m o n t h s after surgery. There is thinning of cortical bone at the lower border of the mandible, and the lesion exhibits a 'scalloped' inferior margin.
Case 2. A 9-year-old boy attended the Children's department of King's College Hospital Dental School for treatment of fractures of his upper incisor teeth. A routine radiograph (Fig. 4) revealed a rather poorly-defined radiolucency in the right mandible involving the roots of 6~ and the mesial root of 7~. T h e r e was no obvious swelling and the boy complained of no s y m p t o m s . 6~ was vital. A provisional diagnosis of central giant-cell lesion was thought most unlikely, and surgery arranged. At operation bloodstained serous fluid was aspirated. After exposure of the bone the lesion was opened to reveal a smooth-walled cavity with no evident lining. No further t r e a t m e n t except w o u n d closure was carried out. Histology revealed bone lined with fibrous connective tissue containing a few giant cells but no epithelium, thus
Fig. 5 - Case 2. Four m o n t h s after surgery. T h e radiolucent area has almost completely resolved. Normal growth of the mesial root of 7~ has continued.
Fig. 4 - Case 2. Section of D P T at presentation,
Fig. 6 - Case 2. A well-defined round area of radiolucency has appeared related to the distal root of 6~, 3 years after surgery.
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CLINICALRADIOLOGY
Fig. 7 - Case 2. The new lesion has extended superiorly and distally, 54 months after original surgery.
DISCUSSION Recurrence of simple bone cysts is far m o r e c o m m o n in the rest of the skeleton than in the jaws: Campanacci et al. (1986) reported incomplete healing in 21% and recurrence in 33% of cases after surgery. In contrast, in the review by H u e b n e r and Turlington (1971) only two out of their 155 cases recurred after treatmenL Therefore, the generally accepted view is that the simple bone cyst of the jaws has an excellent prognosis. The two cases reported here are notable for their behaviour in recurring aggressively after the conventional form of treatment~ Other cases where r e p e a t e d surgery was required before healing occurred have been r e p o r t e d by Lindsay et al. (1966), Vijayaraghavan and Whitlock (1975), Ruprecht and Reid (1975) and Feinberg et al. (1984)o However, as Feinberg et al. (1984) point out, their case was the only one of these in which considerable bony regeneration occurred prior to the re-appearance of the lesion. Thus they argued that whilst their case was a true recurrence, the previously reported cases represented only lesions which were 'refractory' to resolution via standard treatment. Both of the cases presented here showed a greater or lesser degree of b o n y healing before recurrences arose, and a p p e a r to represent genuinely recurrent simple bone cysts. Why the majority of simple bone cysts in the jaws heal quickly and completely, and only a few behave atypically with recurrence, is not clear. The possibility that the two cases presented here were misdiagnosed is unlikely as, both clinically and histologically, the criteria for diagnosis as simple bone cysts were satisfied. It is feasible that the original cause of the lesions was still present after surgery and thus that re-growth was possible, but until the aetiology of simple bone cysts is clarified this hypothesis cannot be tested. Certainly there was no evidence or history of any traumatic incidents after initial surgery in either case. Cowan (1980) suggested that cysts in the jaws might represent two different lesions: a 'typical traumatic bone
cyst' (with .low recurrence rates) and the rarer 'unicameral cyst of the long bones presenting in the jaws' (with a higher rate of recurrence). H o w e v e r , apart f r o m their behaviour, he gave no other evidence for the existence of, and no means of distinguishing between, the two putative types of simple bone cyst. In the long bones recurrence of simple bone cysts seems to be related to four factors: the age of the patient, proximity of the lesion to the epiphyseal growth plate, the size and the multilocularity of the cyst. Neer et al. (1966) found that recurrence was twice as frequent in patients under 10 years of age than in older patients. Campanacci et al. (1986) demonstrated that recurrences were three times as frequent in multilocular as in unilocular lesions, and twice as c o m m o n when the radiographic 'size' was greater than 21 cm 2. The relationship of the cyst to the growth plate has long been considered important: those in contact with or close to the epiphyseal plate are considered to be 'active', and those in the diaphysis 'latent'. Of course, in the mandible there is no related epiphysis, and it is possible that jaw lesions are analogous to diaphyseal long bone lesions with a correspondingly low recurrence rate. This hypothesis seems m o r e feasible than the dual pathology postulated by Cowan (1980). Although the majority of simple bone cysts arising in the jaws heal uneventfully following straightforward surgical treatment, the two cases presented here emphasise that continued follow-up with periodic radiographic examination is essential. Acknowledgements. We would like to thank the radiographers of the Department of Dental Radiology, Mr Barry Pike and his staff in the Department of Photography of King's College School of Medicine and Dentistry, and Mrs Wendy Lyall for preparing the manuscript.
REFERENCES
Beasley, JD (1976). Traumatic cyst of the jaws: report of 30 cases. Journal of the American Dental Association, 92, 145-152. Blum, T (1955). An additional report on traumatic bone cysts. Oral Surgery, Oral Medicine, Oral Pathology, 8, 917-939. Campanacci, M, Capanna, R & Picci, P (1986). Unicameral and aneurysmal bone cysts. Clinical Orthopaedics and Related Research, 204, 25-36. Chapman, PJ & Romanuik, K (1985). Traumatic bone cyst of the mandible; regression followingaspiration. International Journal of Oral Surgery, 14, 290-294. Chigira, M, Mehara, S, Arita, S & Udagawa, E (1983). The aetiology and treatment of simple bone cysts. The Journal of Bone and Joint Surgery, 65--B, 633-637. Cohen, J (1970). Etiology of simple bone cyst. The Journal of Bone and Joint Surgery, 52-A, 1493-1497. Cohen, MA (1984). Hemorrhagic (traumatic) cyst of the mandible associated with a retained root apex. Oral Surgery, Oral Medicine, Oral Pathology, 57, 26-27. Cowan, CG (1980). Traumatic bone cysts of the jaws and their presentation. International Journal of Oral Surgery, 9, 287-291. Daramola, VO, Samuel, I, Awagbe, HA, Kahn, S (1978). Traumatic cyst of the mandible. Journal of Oral Surgery, 36,210-211 (Part 1) and 282-284 (Part 2). De Tomasi, D &Hann, JR (1985). Traumatic bone cyst: report of a case. Journal of the American Dental Association, 111, 56-57. Feinberg, SE, Finklestein, MW, Langley Page, H & Dembo, JB (1984). Recurrent 'traumatic' bone cysts of the mandible. Oral Surgery, Oral Medicine, Oral Pathology, 57, 418-422. Freedman, GL & Beigleman, MB (1985). The traumatic bone cyst: a new dimension. Oral Surgery, Oral Medicine, Oral Pathology, 9, 616-618. Gilman, RH & Dingman, RO (1982). A solitary bone cyst of the
CYSTS OF THE JAWS mandibular condyle. Plastic and Reconstructive Surgery, 70, 610614. Hansen, LS, Sapone, J & Sproat, RC (1974). Traumatic bone cysts of jaws. Oral Surgery, Oral Medicine, Oral Pathology, 37,899-910. Heimdahl, A (1978). An unusual case of 'simple bone cyst' of the mandible. International Journal of Oral Surgery, 7, 32-35. Hillerup, S & Hjorting-Hansen, E (1978). Aneurysmal bone cystsimple bone cyst. Two aspects of the same pathologic entity? International Journal of Oral Surgery, 92, 16-22. Hosseini, M (1978). Two atypical solitary base cysts. British Journal of Oral Surgery, 16, 262-269. Howe, GL (1965). 'Haemorrhagic cysts' of the mandible. British Journal of Oral Surgery, 3, 55-91. Huebner, GR & Turlington, EG (1971). So-called traumatic (hemorrhagic) bone cysts of the jaws. Oral Surgery, Oral Medicine, Oral Pathology, 31,354-365. Jaff6, HL (1953). Giant cell reparative granuloma, traumatic bone cyst and fibrous dysplasia of the jawbones. Oral Surgery, Oral Medicine, Oral Pathology, 6, 159-175. Johnson, LC & Kindred, RG (1958). The anatomy of bone cysts. The Journal of Bone and Joint Surgery (Am), 40--A, 1440. Kuroi, M (1980). Simple bone cyst of the jaw: review of the literature and report of case. Journal of Oral Surgery, 38, 456-459. Lindsay, JS, Martin, WR, Green, H (1966). Traumatic bone cyst treated with homogenous bone graft. Report of a case. Oral Surgery, Oral Medicine, Oral Pathology, 21,536.542. Lucas, RB (1984). Pathology of Tumours of the Oral Tissues. 4th edn. pp. 378-380. Churchill Livingstone, Edinburgh. Mirra, JM, Bernard, GW, Bullough, PG, Johnston, W & Mink, G (1978). Cementum-like bone production in solitary bone cysts (socalled 'cementoma' of long bones). Clinical Orthopaedics and Related Research, 135, 295-307. Mitchell, DA & Ward-Booth, RP (1984). Atypical presentation of a solitary bone cyst. International Journal of Oral Surgery, 13, 256259.
57
M6nckeberg, G (1904). Ueber Cystenbildung bei ostitis fibrosa. Verhandlungen der Deutschen Gesselleschafifur Pathologie, 7, 232241. Narang, R (1980). Large traumatic bone cyst of the mandible. Journal of Oral Surgery, 38, 617-618. Neer, CS, Francis, KC, Marcove, RC, Terz, J & Carbonara, PN (1966). Treatment of unicameral bone cyst. The Journal of Bone and Joint Surgery, 48, 731-745. Olech, E, Sicher, H, Weinmann, JP (1951). Traumatic mandibular bone cyst. Oral Surgery, Oral Medicine, Oral Pathology, 4, 11601172. Persson, G (1985). An atypical solitary bone cyst. Journal of Oral and Maxillofacial Surgery, 43, 905-907. Pommer, G (1920). Zur Kenntnis der Progresiven Hamatom-undPhlegmasie-verandersungen der Rohrenknochen. Archiv fur Orthopadische und Unfall- Chirurgie, 17, 17-69. Raibley, SO, Beckett, RP & Nowakowski, A (1979). Multiple traumatic bone cysts of the mandible. Journal of Oral Surgery, 37, 335-337. Ruprecht, A & Reid, J (1975). Simple bone cyst: report of two cases. Oral Surgery, Oral Medicine, Oral Pathology, 30, 826-832. Rushton, MA (1946). Solitary bone cysts in the mandible. British Dental Journal, 81~ 37-49. Sharma, JN (1983). Hemorrhagic cyst of the mandible in relation to horizontally impacted third molar. Oral Surgery, Oral Medicine, Oral Pathology, 55, 17-18. Szerlip, L (1966). Traumatic bone cysts: resolution without surgery. Oral Surgery, Oral Medicine, Oral Pathology, 21,201-204. Trueta, J (1968). Studies of the Development and Decay of the Human Frame. 1st edn. pp. 78-79. Heinemann, London. Vijayaraghavan, K & Whitlock, RIH (1975). An unusual case of 'haemorrhagic' bone cyst. British Journal of Oral Surgery, 13, 64-72. Winer, RA & Doku HC (1978). Traumatic bone cyst in the maxilla. Oral Surgery, Oral Medicine, Oral Pathology, 46, 367-370.
Atypical Simple Bone Cysts of the Jaws. I: Recurrent Lesions K. H O R N E R , G. H. FORMAN* and N. J. D. SMITH Departments of Dental Radiology and * Oral & Maxillofacial Surgery, The Dental School, King's College School of Medicine and Dentistry, Denmark Hill, London SE5 8 R X The aetiology, clinical and radiographic features and the treatment of simple bone cysts of the jaws are discussed. Recurrence of jaw lesions is unusual. Two cases are presented of simple bone cyst in the mandible which recurred following conventional treatment. The importance of clinical and radiographic follow-up is emphasised.
The simple bone cyst is a pathological cavity lying within bone and lacking any epithelial lining, arising most commonly in the proximal ends of the humerus and femur. A lesion with the same name and features is found in the jaws and is generally considered the same entity (Lucas, 1984). Although Campanacci et al. (1986), who surveyed the skeletal distribution of simple bone cysts, described lesions other than in the humerus and femur as 'definitely rare', they did not include any cases arising in the jaws. Such lesions are not so uncommon as once thought, but do not usually come to the attention of general radiologists and orthopaedic surgeons who are acquainted with the cyst elsewhere in the skeleton. Various names have been coined for the simple bone cyst supposedly to reflect its putative aetiology or appearance (e.g. traumatic, solitary, unicameral, haemorrhagic and extravasation bone cyst) but the term simple bone cyst is preferred here as the most noncommittal. Despite numerous theories, the aetiology of simple bone cysts remains obscure and no individual theory explains all the circumstances in which the lesions are found. M6nckeberg (1904) proposed that bone cysts were healing giant cell tumours or osteitis fibrosa. A relationship to giant cell tumours was further suggested by Rushton (1946), with some circumstantial support subsequently reported by Huebner and Turlington (1971) and Hillerup and Hjorting-Hansen (1978). Apart from this there are two important theories of possible aetiologies: one supports a haemorrhagic cause, the other a developmental origin. The haemorrhagic theory depends upon the formation of an intra-medullary haematoma following either arterial (Pommer, 1920) or venous (Olech et al., 1951) bleeding within bone. This possibly could occur following trauma which is either too slight, or of a type (e.g. compressive, torsional) insufficient to cause a fracture. Instead of undergoing normal organisation and healing it is suggested that such a haematoma might lyse and the involved bone resorb, to leave a bony 'space'. Subsequently, perhaps involving factors such as poor venous drainage (Cohen, 1970) and a high intracystic hydrostatic pressure (Chigira etal., 1983), this could develop into the bone cavity recognised as a simple bone cyst. The jaws are a frequent site of trauma, and there has been much discussion on its relationship to cyst development in the literature. However, the objective recording of a history of trauma is difficult, and such disparate figures of between 26.9% (Beasley, 1976) and 81% (Hansen et
al., 1974) of patients giving such a history underlines that the traumatic theory of origin is not proven. Jaffd (1953) first postulated that the simple bone cyst was a developmental 'aberration'. Hosseini (1978), suggested that it could arise in development by metaplasia of osteogenic into synovial cells, as produced experimentally by Trueta (1968), forming multiple synovial cavities which coalesce to form a fluid-containing cyst. There is support for this in the work of both Johnson and Kindred (1958), who reported a resemblance between synovial bursae and cyst linings, and Mirra et al., (1978) who claimed to find 'unmistakable' synovial cells in the walls of the simple bone cyst of the femur. Such a theory is in accordance with the sites of predilection of the lesion close to the synovial-capsular-bone reflection in the long bones, but fails to explain why the temporomandibular joint is a rare site of occurrence for jaw lesions. It is suggested that the latter anomaly is related to the unusual growth pattern of the mandible, permitting translocation of potential lesions into the toothbearing regions (Hosseini 1978). Jaw lesions are usually fortuitous discoveries on routine dental radiographs, between 60 and 80% of patients being quite asymptomatic (Howe, 1965; Beasley, 1976). When symptoms occur, the commonest are swelling and pain (Huebner and Turlington, 1971). With mandibular lesions, disturbed labial sensation (De Tomasi and Hann, 1985) and pathological fracture (Cowan, 1980) have been reported as rare presenting signs. As with long bone lesions, most cysts arise in children with a peak incidence in the second decade (Howe, 1965; Huebner and Turlington, 1971). There is a small but consistent predilection for the development of cysts in males (Howe, 1965; Kuroi, 1980). It is unusual for cysts to arise outside the tooth-bearing parts of the jaws, thus corresponding to the sites of haemopoietic bone marrow (Howe, 1965). However, isolated cases have arisen in the mandibular condyle (Gilman and Dingman, 1982; Persson, 1985). Lesions are more common in the mandible than in the maxilla, the latter constituting between 11% (Kuroi, 1980) and 32% (Hansen et al., 1974) of the total of jaw lesions. In the mandible the molar regions are favoured sites while in the maxilla the intercanine region is usually affected. Expansion occurs in a minority of cases, but when present is usually bucco-labial (Howe, 1965). Associated teeth maintain normal vitality and are rarely displaced by the lesion (Huebner and Turlington, 1971). Radiologically the classic appearance of the simple bone cyst is a well-defined radiolucency with a very characteristic 'scalloped' appearance where it extends between the roots of the teeth (Lucas, 1984). However, the appearance commonly departs from these 'typical' features, and Hansen et al. (1974) concluded that the size, shape, margins and degree of radiolucency were quite variable. Thus simple bone cysts have been misdiagnosed prior to surgery as dentigerous cysts (Sharma, 1983), radicular cysts (Winer and Doku, 1978) and
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CLINICAL RADIOLOGY
r e s i d u a l cysts ( C o h e n , 1984). L e s i o n s a r e u s u a l l y single b u t o c c a s i o n a l l y m u l t i p l e ( H e i m d a h l , 1978; R a i b l e y et al., 1979), a n d g r e a t size m a y b e a t t a i n e d b e f o r e d e t e c tion ( F r e e d m a n a n d B e i g l e m a n , 1985). M u l t i l o c u l a r i t y is an o c c a s i o n a l f i n d i n g ( N a r a n g , 1980; M i t c h e l l a n d W a r d - B o o t h , 1984) a n d it is this m o r e t h a n a n y o t h e r f a c t o r which m a y c o n f u s e d i f f e r e n t i a l d i a g n o s i s a n d suggest an aggressive l e s i o n such as a m e l o b l a s t o m a , prim o r d i a l cyst or o d o n t o g e n i c m y x o m a . H o w e v e r , t h e l a m i n a d u r a a r o u n d a s s o c i a t e d t e e t h r e m a i n s intact ( C h a p m a n a n d R o m a n i u k , 1985) a n d r o o t r e s o r p t i o n is an e x t r e m e l y r a r e f i n d i n g ( D a r a m o l a et al., 1978). S u r g e r y r e m a i n s t h e first c h o i c e o f t r e a t m e n t for simple b o n e cysts of t h e j a w s , n o t least b e c a u s e d e f i n i t i v e diagnosis can o n l y b e m a d e a f t e r surgical e x p l o r a t i o n . Surgical access to t h e j a w s is s t r a i g h t f o r w a r d , a n d t h e f o r m a t i o n of a ' w i n d o w ' into the cavity, w i t h c u r e t t a g e of the walls to p r o m o t e b l e e d i n g a n d h a e m a t o m a f o r m a tion, r e a d i l y l e a d s to its r e s o l u t i o n b y b o n y r e g e n e r a tion. Other treatments, such as i n j e c t i o n of m e t h y l p r e d n i s o l o n e a c e t a t e into cysts a n d the use of b o n e grafts a r e n o t c o n v e n t i o n a l p r a c t i c e . A t s u r g e r y , cysts m a y b e e m p t y o r c o n t a i n v a r i a b l e a m o u n t s o f fluid usually d e s c r i b e d as s e r o s a n g u i n o u s , a l t h o u g h w h o l e blood may be encountered (Chapman and Romaniuk, 1985). H o w e (1965) b e l i e v e d ' d r y cavities' r e p r e s e n t o l d e r lesions. T h e e v i d e n c e for s p o n t a n e o u s r e g r e s s i o n o f s i m p l e b o n e cyst is n o t c o m p l e t e l y p r o v e n , as diagnosis of s i m p l e b o n e cyst was m a d e w i t h o u t surgical o r histological e v i d e n c e in t h e cases r e p o r t e d ( B l u m , 1955; Szerlip, 1966). P a t h o l o g i c a l s p e c i m e n s a r e c o m m o n l y little m o r e t h a n a few b o n y f r a g m e n t s . This p a u c i t y of m a t e r i a l r e m a i n s a p r o b l e m in f u r t h e r i n g k n o w l e d g e of t h e p a t h o l o g y o f s i m p l e b o n e cyst. H o w e v e r , it is c l a i m e d by G i l m a n a n d D i n g m a n (1982) t h a t o n careful e x a m i n a tion a lining, a l b e i t s c a n t y , is always f o u n d consisting of c o n n e c t i v e tissue, g r a n u l a t i o n tissue, o s t e o b l a s t s a n d osteoclasts. E x t r a v a s a t e d r e d b l o o d cells a n d h a e m o siderin d e p o s i t s a r e also f o u n d ( B e a s l e y , 1976). E p i thelial cells a r e n e v e r f o u n d o r d e s c r i b e d in t h e r e p o r t s in t h e d e n t a l l i t e r a t u r e . H o w e v e r , in cysts of the f e m u r M i r r a et al. (1978) h a v e r e p o r t e d cells with basal l a m i n a e (i.e. e p i t h e l i a l cells) in t h e c o n n e c t i v e tissue lining i d e n tifiable as s y n o v i a l ' A ' a n d ' B ' cells. N o such s e a r c h has b e e n c a r r i e d o u t for e p i t h e l i a l cells b y o r a l p a t h o l o g i s t s as far as w e k n o w , a n d such r e s e a r c h w o u l d b e of h e l p in the e v a l u a t i o n of t h e s y n o v i a l t h e o r y ( M i r r a et al., 1978; H o s s e i n i , 1978) o f o r i g i n for s i m p l e b o n e cysts. T h e p r o g n o s i s f o l l o w i n g c o n v e n t i o n a l t r e a t m e n t is v e r y g o o d a n d r e c u r r e n c e is r a r e . T h e a v e r a g e t i m e f r o m o p e r a t i o n to c o m p l e t e h e a l i n g has b e e n r e p o r t e d as just o v e r 12 m o n t h s ( H u e b n e r a n d T u r l i n g t o n , 1971).
Fig. 1 - Case 1. Section of dental panoramic tomogram (DPT) taken at initial presentation, demonstrating the radiolucent lesion in the right body of mandible.
A provisional diagnosis of simple bone cyst was made and the patient admitted for surgery. Upon raising a buccal mucoperiosteal flap, only a bluish eggshell-thin layer of bone was present overlying the cavity. On gaining access to the lesion it was found to contain clear fluid but no obvious lining. The cavity was allowed to fill with blood and the wound closed. Healing was uneventful and after 6 months considerable bony regeneration has recurred (Fig. 2). However, after a further year radiographs showed a recurrence, with growth of a new lesion even larger than the original (Fig. 3), extending from the 81 region across the midline as far as ~, with 'scalloping' at the lower border of the mandible. A second, more extensive, operation was performed. Prior to opening the cavity aspiration yielded clear fluid. The lesion was then entered but contained no peripheral lining. However, it was noted that, adjacent to the roots of the teeth, there were a number of separate, intact, fluidcontaining saccules; these burst to release clear fluid on only slight manipulation. The bony window was extended to include the entire buccal wall of the cavity, fragments of the removed bone being retained for histological examination. The wound was closed conventionally. After 10 months there was radiographic evidence of considerable bonyfegeneration; all the previously involved teeth were vital, including 761 which had given non-vital response to careful testing at the time of the original lesion.
CASE REPORTS Case 1. A 13-year-old girl was referred by her general dental practitioner with regard to a radiolucent 'cystic' area observed radiographically in the right side of her mandible. The patient was symptomless. On examination a slight intra-oral swelling was observed buccal to the lower right molar teeth. 7~ gave a non-vital response to electric pulp testing despite being caries-free. Radiographs revealed a large radiolucency in the right mandible which extended superiorly between the roots of 7654] and showed some thinning of the cortical plate at the lower border of the mandible in relation to the lesion (Fig. 1). Faint bony septae were visible running almost verticallyfrom the apices of 654] to the lower wall of the defect.
Fig. 2 - Case 1. At 6 months after surgery the site of the lesion shows a large degree of bony regeneration.
CYSTS OF THE JAWS
55
supporting the clinical appearance of a simple bone cyst. Healing proceeded well, and after 6 m o n t h s m u c h bone had formed in the site of the lesion (Fig. 5). However, 3 years after surgery radiography demonstrated recurrence of the radiolucency in the origin~/l site (Fig. 6). After a further 18 m o n t h s of observation the new lesion had increased in size (Fig. 7) and further surgery was considered to be necessary. This was carried out following the same procedure as previously. At surgery, following aspiration of 5 ml of 'red fluid' the lesion was opened to reveal a rough-walled cavity without a lining. Closure of the wound was then effected. Protein electrophoresis of cyst fluid showed a normal s e r u m pattern, and histology of the wall of the lesion demonstrated a lining of fibrous connective tissue with m a n y osteoblasts and osteoclasts. Therefore, once again the histology confirmed the clinical diagnosis of simple bone cyst.
Fig. 3 - Case 1. A n e w radiolucent lesion is present extending across the mid-line 18 m o n t h s after surgery. There is thinning of cortical bone at the lower border of the mandible, and the lesion exhibits a 'scalloped' inferior margin.
Case 2. A 9-year-old boy attended the Children's department of King's College Hospital Dental School for treatment of fractures of his upper incisor teeth. A routine radiograph (Fig. 4) revealed a rather poorly-defined radiolucency in the right mandible involving the roots of 6~ and the mesial root of 7~. T h e r e was no obvious swelling and the boy complained of no s y m p t o m s . 6~ was vital. A provisional diagnosis of central giant-cell lesion was thought most unlikely, and surgery arranged. At operation bloodstained serous fluid was aspirated. After exposure of the bone the lesion was opened to reveal a smooth-walled cavity with no evident lining. No further t r e a t m e n t except w o u n d closure was carried out. Histology revealed bone lined with fibrous connective tissue containing a few giant cells but no epithelium, thus
Fig. 5 - Case 2. Four m o n t h s after surgery. T h e radiolucent area has almost completely resolved. Normal growth of the mesial root of 7~ has continued.
Fig. 4 - Case 2. Section of D P T at presentation,
Fig. 6 - Case 2. A well-defined round area of radiolucency has appeared related to the distal root of 6~, 3 years after surgery.
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CLINICALRADIOLOGY
Fig. 7 - Case 2. The new lesion has extended superiorly and distally, 54 months after original surgery.
DISCUSSION Recurrence of simple bone cysts is far m o r e c o m m o n in the rest of the skeleton than in the jaws: Campanacci et al. (1986) reported incomplete healing in 21% and recurrence in 33% of cases after surgery. In contrast, in the review by H u e b n e r and Turlington (1971) only two out of their 155 cases recurred after treatmenL Therefore, the generally accepted view is that the simple bone cyst of the jaws has an excellent prognosis. The two cases reported here are notable for their behaviour in recurring aggressively after the conventional form of treatment~ Other cases where r e p e a t e d surgery was required before healing occurred have been r e p o r t e d by Lindsay et al. (1966), Vijayaraghavan and Whitlock (1975), Ruprecht and Reid (1975) and Feinberg et al. (1984)o However, as Feinberg et al. (1984) point out, their case was the only one of these in which considerable bony regeneration occurred prior to the re-appearance of the lesion. Thus they argued that whilst their case was a true recurrence, the previously reported cases represented only lesions which were 'refractory' to resolution via standard treatment. Both of the cases presented here showed a greater or lesser degree of b o n y healing before recurrences arose, and a p p e a r to represent genuinely recurrent simple bone cysts. Why the majority of simple bone cysts in the jaws heal quickly and completely, and only a few behave atypically with recurrence, is not clear. The possibility that the two cases presented here were misdiagnosed is unlikely as, both clinically and histologically, the criteria for diagnosis as simple bone cysts were satisfied. It is feasible that the original cause of the lesions was still present after surgery and thus that re-growth was possible, but until the aetiology of simple bone cysts is clarified this hypothesis cannot be tested. Certainly there was no evidence or history of any traumatic incidents after initial surgery in either case. Cowan (1980) suggested that cysts in the jaws might represent two different lesions: a 'typical traumatic bone
cyst' (with .low recurrence rates) and the rarer 'unicameral cyst of the long bones presenting in the jaws' (with a higher rate of recurrence). H o w e v e r , apart f r o m their behaviour, he gave no other evidence for the existence of, and no means of distinguishing between, the two putative types of simple bone cyst. In the long bones recurrence of simple bone cysts seems to be related to four factors: the age of the patient, proximity of the lesion to the epiphyseal growth plate, the size and the multilocularity of the cyst. Neer et al. (1966) found that recurrence was twice as frequent in patients under 10 years of age than in older patients. Campanacci et al. (1986) demonstrated that recurrences were three times as frequent in multilocular as in unilocular lesions, and twice as c o m m o n when the radiographic 'size' was greater than 21 cm 2. The relationship of the cyst to the growth plate has long been considered important: those in contact with or close to the epiphyseal plate are considered to be 'active', and those in the diaphysis 'latent'. Of course, in the mandible there is no related epiphysis, and it is possible that jaw lesions are analogous to diaphyseal long bone lesions with a correspondingly low recurrence rate. This hypothesis seems m o r e feasible than the dual pathology postulated by Cowan (1980). Although the majority of simple bone cysts arising in the jaws heal uneventfully following straightforward surgical treatment, the two cases presented here emphasise that continued follow-up with periodic radiographic examination is essential. Acknowledgements. We would like to thank the radiographers of the Department of Dental Radiology, Mr Barry Pike and his staff in the Department of Photography of King's College School of Medicine and Dentistry, and Mrs Wendy Lyall for preparing the manuscript.
REFERENCES
Beasley, JD (1976). Traumatic cyst of the jaws: report of 30 cases. Journal of the American Dental Association, 92, 145-152. Blum, T (1955). An additional report on traumatic bone cysts. Oral Surgery, Oral Medicine, Oral Pathology, 8, 917-939. Campanacci, M, Capanna, R & Picci, P (1986). Unicameral and aneurysmal bone cysts. Clinical Orthopaedics and Related Research, 204, 25-36. Chapman, PJ & Romanuik, K (1985). Traumatic bone cyst of the mandible; regression followingaspiration. International Journal of Oral Surgery, 14, 290-294. Chigira, M, Mehara, S, Arita, S & Udagawa, E (1983). The aetiology and treatment of simple bone cysts. The Journal of Bone and Joint Surgery, 65--B, 633-637. Cohen, J (1970). Etiology of simple bone cyst. The Journal of Bone and Joint Surgery, 52-A, 1493-1497. Cohen, MA (1984). Hemorrhagic (traumatic) cyst of the mandible associated with a retained root apex. Oral Surgery, Oral Medicine, Oral Pathology, 57, 26-27. Cowan, CG (1980). Traumatic bone cysts of the jaws and their presentation. International Journal of Oral Surgery, 9, 287-291. Daramola, VO, Samuel, I, Awagbe, HA, Kahn, S (1978). Traumatic cyst of the mandible. Journal of Oral Surgery, 36,210-211 (Part 1) and 282-284 (Part 2). De Tomasi, D &Hann, JR (1985). Traumatic bone cyst: report of a case. Journal of the American Dental Association, 111, 56-57. Feinberg, SE, Finklestein, MW, Langley Page, H & Dembo, JB (1984). Recurrent 'traumatic' bone cysts of the mandible. Oral Surgery, Oral Medicine, Oral Pathology, 57, 418-422. Freedman, GL & Beigleman, MB (1985). The traumatic bone cyst: a new dimension. Oral Surgery, Oral Medicine, Oral Pathology, 9, 616-618. Gilman, RH & Dingman, RO (1982). A solitary bone cyst of the
CYSTS OF THE JAWS mandibular condyle. Plastic and Reconstructive Surgery, 70, 610614. Hansen, LS, Sapone, J & Sproat, RC (1974). Traumatic bone cysts of jaws. Oral Surgery, Oral Medicine, Oral Pathology, 37,899-910. Heimdahl, A (1978). An unusual case of 'simple bone cyst' of the mandible. International Journal of Oral Surgery, 7, 32-35. Hillerup, S & Hjorting-Hansen, E (1978). Aneurysmal bone cystsimple bone cyst. Two aspects of the same pathologic entity? International Journal of Oral Surgery, 92, 16-22. Hosseini, M (1978). Two atypical solitary base cysts. British Journal of Oral Surgery, 16, 262-269. Howe, GL (1965). 'Haemorrhagic cysts' of the mandible. British Journal of Oral Surgery, 3, 55-91. Huebner, GR & Turlington, EG (1971). So-called traumatic (hemorrhagic) bone cysts of the jaws. Oral Surgery, Oral Medicine, Oral Pathology, 31,354-365. Jaff6, HL (1953). Giant cell reparative granuloma, traumatic bone cyst and fibrous dysplasia of the jawbones. Oral Surgery, Oral Medicine, Oral Pathology, 6, 159-175. Johnson, LC & Kindred, RG (1958). The anatomy of bone cysts. The Journal of Bone and Joint Surgery (Am), 40--A, 1440. Kuroi, M (1980). Simple bone cyst of the jaw: review of the literature and report of case. Journal of Oral Surgery, 38, 456-459. Lindsay, JS, Martin, WR, Green, H (1966). Traumatic bone cyst treated with homogenous bone graft. Report of a case. Oral Surgery, Oral Medicine, Oral Pathology, 21,536.542. Lucas, RB (1984). Pathology of Tumours of the Oral Tissues. 4th edn. pp. 378-380. Churchill Livingstone, Edinburgh. Mirra, JM, Bernard, GW, Bullough, PG, Johnston, W & Mink, G (1978). Cementum-like bone production in solitary bone cysts (socalled 'cementoma' of long bones). Clinical Orthopaedics and Related Research, 135, 295-307. Mitchell, DA & Ward-Booth, RP (1984). Atypical presentation of a solitary bone cyst. International Journal of Oral Surgery, 13, 256259.
57
M6nckeberg, G (1904). Ueber Cystenbildung bei ostitis fibrosa. Verhandlungen der Deutschen Gesselleschafifur Pathologie, 7, 232241. Narang, R (1980). Large traumatic bone cyst of the mandible. Journal of Oral Surgery, 38, 617-618. Neer, CS, Francis, KC, Marcove, RC, Terz, J & Carbonara, PN (1966). Treatment of unicameral bone cyst. The Journal of Bone and Joint Surgery, 48, 731-745. Olech, E, Sicher, H, Weinmann, JP (1951). Traumatic mandibular bone cyst. Oral Surgery, Oral Medicine, Oral Pathology, 4, 11601172. Persson, G (1985). An atypical solitary bone cyst. Journal of Oral and Maxillofacial Surgery, 43, 905-907. Pommer, G (1920). Zur Kenntnis der Progresiven Hamatom-undPhlegmasie-verandersungen der Rohrenknochen. Archiv fur Orthopadische und Unfall- Chirurgie, 17, 17-69. Raibley, SO, Beckett, RP & Nowakowski, A (1979). Multiple traumatic bone cysts of the mandible. Journal of Oral Surgery, 37, 335-337. Ruprecht, A & Reid, J (1975). Simple bone cyst: report of two cases. Oral Surgery, Oral Medicine, Oral Pathology, 30, 826-832. Rushton, MA (1946). Solitary bone cysts in the mandible. British Dental Journal, 81~ 37-49. Sharma, JN (1983). Hemorrhagic cyst of the mandible in relation to horizontally impacted third molar. Oral Surgery, Oral Medicine, Oral Pathology, 55, 17-18. Szerlip, L (1966). Traumatic bone cysts: resolution without surgery. Oral Surgery, Oral Medicine, Oral Pathology, 21,201-204. Trueta, J (1968). Studies of the Development and Decay of the Human Frame. 1st edn. pp. 78-79. Heinemann, London. Vijayaraghavan, K & Whitlock, RIH (1975). An unusual case of 'haemorrhagic' bone cyst. British Journal of Oral Surgery, 13, 64-72. Winer, RA & Doku HC (1978). Traumatic bone cyst in the maxilla. Oral Surgery, Oral Medicine, Oral Pathology, 46, 367-370.