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Juvenile ossifying fibroma
J. Cranio-Max.-Fac. Surg. 18 (1990) J. Cranio-Max.-Fac. Surg. 18 (1990) 125-129 © Georg ThiemeVerlag Stuttgart • New York
125
Summary The present investigation concerns 4 patients with juvenile ossifying fibroma (JOF) whose data are analyzed together with 30 cases from the literature. The tumour mainly occurs in juveniles, 79 % of the patients being 15 years or younger. Radiologically as well as at surgery, the lesion is demarcated from its surroundings. Histologically, JOF is unique in showing a loose-fibroblastic stroma that contains garlandlike strands of osteoid with entrapped osteoblasts, the latter feature not being observed in other fibro-osseous lesions. JOF responds very well to conservative treatment that provided permanent cure in all cases with adequate follow-up data.
Juvenile Ossifying Fibroma Report of Four Cases Pieter J. Slootweg ~, Hellmuth Miiller 2 1Institute of Pathology(Head: Prof. J. A. M. van Unnik, M.D.), University of Utrecht zClinic for Maxillofacial Surgery(Head:Dr. H. Mfiller,M.D., D.M.D.), University Hospital Utrecht, The Netherlands Submitted 3.7. 1989; accepted 29.8. 1989
Key words Fibro-osseous lesion - Juvenile ossifying fibroma Jaw tumours
Introduction The group of fibro-osseous lesions of the maxillofacial skeleton includes an ill-defined entity known under a plethora of designations: young ossifying fibroma (Smith and Zavaleta, 1952; Fu and Perzin, 1974), juvenile ossifying fibroma (Reed and Hagy, 1965; Pindborg and HjortingHansen 1974; Test et al., 1976; Scharffetter et al., 1986), active juvenile ossifying fibroma (Waldron, 1985; Hoffman et al., 1987), aggressive ossifying fibroma (Walter et al., 1979; Reaume et al., 1985), juvenile aggressive ossifying fibroma (Putschar, 1974; Eversole et al., 1985) and trabecular desmo-osteoblastoma (Makek, 1983). Reports concerning this lesion are usually limited to single cases and with one exception (Makek, 1983) there have been no series from which data on clinical behaviour and histological spectrum can be inferred. Therefore, we considered it useful to report our experience with this lesion for which we employ the provisional designation "juvenile ossifying fibroma" (JOF).
Results Data on age, sex and location of the cases from the literature are presented in Table 1. Comparable data on our own cases are presented in Table 2 together with data on treatment and follow-up. All cases had swelling as the presenting symptom (Fig. 1), Case 1 had been seen for the first time in 1952 but for technical reasons definitive treatment was postponed until 7 years later, a time span during which the tumour had gradually increased in size. Radiographs were available of cases 1-3. Cases i and 3
Materials and Methods
Table I
Cases of juvenile ossifying fibroma from the literature
All benign fibro-osseous lesions presenting through the Oral Pathology Department of t h e Utrecht University were reviewed and 4 were considered to represent cases of JOF on the basis of clinical evidence of t u m o u r and histopathological features compatible with that diagnosis as they were provisionally defined, using reported data. These features include a cell-rich fibroblastic stroma, occasionally exhibiting a storiform pattern and highly cellular cords of osteoblasts appearing to be incorporated in osteoid (Pindborg and Hjerting-Hansen, 1974; Waldron, 1985). The data were extended by including cases from the literature that were reported under one of the designations mentioned in the introduction and by including cases not reported as JOF but warranting that diagnosis by their histopathological features as presented and illustrated in case reports (Dehner, 1973; Adekeye et al., 1980; Krumholz et al., 1986). The histological findings of JOF were compared with those encountered in 11 cases of radiologically, clinically and histologically well-demarcated fibro-osseous lesions representing ossifying fibroma (OF) conforming to established criteria (Eversole et al., 1985).
Mean age in years
Male/female
Location
12.2
19/11
maxilla 16 mandible 13 ethmoid 1
Table2
Present cases of juvenile ossifying fibroma
Case Sex
Age*
Location
Treatment
Follow-up
10 9 3 12
maxilla mandible maxilla maxilla
resection enucleation enucleation enucleation
NED** after 30 years NED after 5 years NED after 13 years recurrence after 3.5 and 10 years thereafter NED after 22 years
no.
1 2 3 4
F F M F
* in years ** No evidence of disease
126
J. Cranio-Max.-Fac. Surg. 18 (1990)
Fig. 1 Case 1. Tumour causes considerable deformity of the left side of the face, Appearance at time of surgical treatment after 7 years of clinical observation,
P. J. Slootweg, H. Miiller
Fig. 2 Case 1. Radiograph in a cranio-caudal direction shows expansion of the left maxilla. The lesion is mixed radiodense-radiolucent and the cortical bone is visible as a demarcated radiodense line.
Fig.3 Case 2. Radiograph shows expansion of the left mandibular ramus due to a lesion with a ground glass appearance. Bordering cortical bone is observed as a distinct radiodense line,
were mixed radiolucent-radiopaque with vaguely outlined radiodense areas (Fig. 2) and case 2 exhibited a mildly radiopaque homogeneous appearance mimicking a ground glass pattern (Fig. 3). From case 4, radiographs were available of the lesion when initially seen and at the time of operation, 7 years later. During that time, the lesion had become more radiodense. All lesions were well circumscribed without blending into the normal surrounding bone and an expanded cortical layer could be discerned as a radiodense line bordering the lesion (Fig. 2). Histologically, all four cases were
characterized by the presence of loose fibrous tissue with spindle-shaped fibroblasts exhibiting ovoid nuclei with finely granular chromatin. Mitotic figures were present in all lesions although their number varied among individual cases. In all lesions, there were focal collections of multinucleated giant cells, mostly in areas of cystic degeneration, oedema and haemorrhage but also unrelated to these stromal alterations. All lesions exhibited bone formation as follows. There were focal aggregates of large plump eosinophilic cells resembling osteoblasts that appeared to be incorporated in a
Juvenile Ossifying Fibroma
J. Cranio-Max.-Fac. Surg. 18 (1990)
12 7
Fig.4 Photomicrograph shows typical appearance of JOF consisting of strands of osteoid with entrapped cells in a loose fibrillary background tissue (HE x 75).
Fig. 5 The strands of osteoid are irregularly mineralized and bordered by osteoblasts (HE x 120),
Fig. 6 Sometimes the osteoblastic rimming of woven bone trabeculae may be very prominent. Osteoclasts are also present at the border of the bone (HE x 75)
Fig. 7 The bony component may increase to a proportionally large size together with decreased cellularity of the stroma. The woven nature of the bone is nevertheless retained (HE x 75).
dense-fibrillary osteoid m a t r i x that surrounded them. These areas of osteoid with e n t r a p p e d cells fused to f o r m anastomosing cords that merged with irregularly calcified trabeculae of woven bone rimmed by p l u m p osteoblasts and osteoclasts (Figs. 4-6). Lamellar bone was not observed. In cases 1 and 4 tissue was removed on several occasions over a time span of 6 to 10 years. In these cases, a kind of
m a t u r a t i o n was observed, in the sense that there were stromal areas with a decreased cellularity where the cells were surrounded by a fine-fibrillar, pale-staining collagenous matrix. In both cases, this p a t t e r n was not observed at the time of inital presentation. M o r e o v e r the b o n y component had p r o p o r t i o n a l l y g r o w n larger and the b o n y trabeculae were coarse and had sometimes coalesced to areas with little intervening stroma remaining (Fig. 7), but the
128
]. Cranio-Max.-Fac.Surg. 18 (1990)
Table3
Present cases of ossifying fibroma
Mean age in years
Male/female
Location
25.1
7/4
maxilla 4 mandible 6 ethmoid 1
bony component had retained its woven nature, maturation towards lamellar bone being absent. In all cases, the available slides permitted evaluation of the boundary between tumour and surrounding jaw bone; the lesion was circumscribed and there was no blending of the lesional bone with the expanded cortical layer or the medullary bone spongiosa. An apparent fibrous capsule was, however, lacking in all cases, the tumour stroma being in immediate contact with the surrounding jaw bone. Histological examination of the 11 OF cases showed these to have a rather varying appearance; stroma varied from hyaline or fibrous to cellular and the mineralized material included woven bone, lamellar bone, spheroid basophilic particles that were interpreted as cementicles and smoothly contoured, curvilinear, cell-poor trabeculae. Woven bone was the only feature common to OF as well as JOF. Clinical data of the 11 OF cases are shown in Table 3. Discussion The data from the literature and the present cases lead to the following conclusions on JOF. Age distribution and mean age of the cases warrant the adjective juvenile; only 21% of the patients is older than 15 years. A site of predilection is not apparently present, upper and lower jaw being almost equally involved; extragnathic cases are rare. The presenting clinical symptom is swelling. The growth rate is variable, case 2 exhibited a rapid growth whereas cases 1 and 4 steadily increased in size. The radiological features are variable. Depending on the extent of ossification, the uni- or multilocular lesion may be radiolucent or mixed radiolucent-radiodense but there is always a distinct radiodense border. Our case 1 serves to illustrate that an initially radiolucent lesion may become more radiodense when left in situ. Lesions have been reported to be removed by radical resection (Smith and Zavaleta, 1952; Putschar, 1974) or in a conservative way by local excision or enucleation with subsequent curettage (Smith and Zavaleta, 1952; Fu and Perzin, 1974; Test et al., 1976; Makek, 1983; Reaume et al., 1985). Data from the literature as well as our own follow-up data (Table 2) indicate that all patients have been cured of their tumour although some required two or more surgical attempts because of recurrent turnout. As there is no difference in outcome between patients treated in a more limited way and those treated by major surgery, it seems appropriate to recommend a conservative surgical approach when managing JOF. The present data do not support the assumption that JOF may be locally invasive and may be fatal (Reed and Hagy, 1965). Moreover, we have not been able to trace any documented report of a case of JOF transforming into osteosarcoma, a possibility mentioned in discussions on JOF (Hoffman et al., 1987). Concerning the histomorphology, data from the literature
P.J. Slootweg, H. Mi~ller and the present cases allow the following outlines to be drawn. The tumour is composed of a loose fibrilar stroma containing numerous fibroblasts. The fibroblasts have vesicular nuclei and predominant nucleoli indicating their very active nature. Mitoses are present but are not very numerous. Throughout the fibrous stroma there are garland-like strands of osteoblasts with interspersed osteoid that are continuous with trabeculae of woven bone with an osteoblastic rim. The stroma may exhibit areas of haemorrhage and cystic degeneration and preferably in these parts, osteoclast-like giant cells may be very numerous. Histologically, the lesion is well demarcated from its surroundings. The tumour does not show a great propensity to maturation, defined as progression towards an end-stage in which the lesion exclusively consists of calcified material. In our cases 1 and 4 who yielded material for histological investigation on several occasions, cell-rich stroma remained identifiable throughout the whole time and none of the available reports mentioned a substantial alteration in tumour morphology related to duration of symptoms. Whether the tumour exhibits maturation from woven towards lamellar bone is uncertain. Presence of lamellar bone is sometimes reported (Reed and Hagy, 1965) but not mentioned to be present by others (Putschar, 1974; Walter et al., 1979; Makek, 1983; Hoffman et al., 1987) and nor was it observed by us. H o w is JOF to be distinguished from other fibro-osseous jaw lesions? The clinical and radiological demarcation between the lesion and the surrounding tissue preclude considering JOF as a variant of fibrous dysplasia as this latter lesion typically blends imperceptibly into the adjacent bone (Waldron, 1985). As far as histology is concerned, JOF can be distinguished from fibrous dysplasia by the very prominent osteoblastic rimming of the bony trabeculae and by the demarcation between lesional bone and adjacent jaw bone provided that surrounding tissue is included in the biopsy specimen. Thus, clinical, radiological and histological characteristics are different and speak against considering JOF a variant of fibrous dysplasia (Adekeye et al., 1980). Moreover, the continuous growth that is shown by JOF refutes a dysplastic nature and makes it more appropriate to consider JOF a neoplasm. The next question is whether there is any reason to distinguish between JOF and OF. Clinical, radiological and histological characteristics agree, as in both they point towards a sharp delineation between turnout and surrounding tissue. There are, however, diverging features warranting separation of JOF from OF. JOF occurs at a far lower mean age than OF: 8.5 years as opposed to 25.1 years in our own OF cases and 36 years in another OF series (Eversole et al., 1985). Moreover, OF contains lamellar bone and cementicles as well as smoothly contoured, cell-poor, curvilinear trabeculae; features that are absent in JOF whereas the osteoblastic cords and the loose, active-appearing fibrous stroma that characterize JOF are absent in OF. It appears that histomorphology is specific enough to make separate categorization of JOF and OF possible. We conclude that within the group of craniofacial fibroosseous lesions, JOF is an entity in its own right: histologically unique in showing highly cellular garland-like strands with entrapped osteoblasts, radiologically, clinically and histologically well-demarcated from its surroundings and amenable to conservative treatment.
Juvenile Ossifying Fibrorna References
Adekeye, E. 0., M. B. Edwards, G. E. Goubran: Fibro-osseous lesions of the skull, face and jaws in Kaduna, Nigeria. Br. J. Oral Surg. 18 (1980) 57 Dehner, L. P.: Tumors of the mandible and maxilla in children. I. Clinicopathologic study of 46 histologically benign lesions. Cancer 31 (1973) 364 Eversole, L. R., A. S. Leider, K. Nelson: Ossifying fibroma: a clinicopathologic study of sixty-four cases. Oral Surg. 60 (1985) 505 Fu, Y. S., K. H. Perzin: Non-epithelial tumors of the nasal cavity, paranasal sinuses, and nasopharynx: a clinico-pathologic study. II. Osseous and fibro-osseous lesions, including osteoma, fibrous dysplasia, ossifying fibroma, osteoblastoma, giant cell tumor, and osteosarcoma. Cancer 33 (1974) 1289 Hoffman, S., J. R. Jacoway, S. O. KrolIs: Intraosseous and parosteal tumors of the jaws. Atlas of tumor pathology, 2th series, fascicle 24. Armed Forces Institute of Pathology, Washington (1987) 208 Krumholz, K., E. Kri~ger, G. Kn~pfle: Verlaufsform des zentralen Fibroms. In: Fortschritte der Kiefer- und Gesichtschirurgie, ein Jahrbuch. Band XXXI. Knochentumoren und Systemerkrankungen im Kiefer-Gesichtsbereich. Thieme, Stuttgart (1986) 25 Makek, M.: Clinical pathology of fibro-osteo-cemental lesions in the cranio-facial and jaw bones. A new approach to differential diagnosis. Karger, Basel (1983) 162 Pindborg, J. J., E. Hj~rting-Hansen: Atlas of diseases of the jaws. Munksgaard, Copenhagen (1974) 68
J. Cranio-Max.-Fac. Surg. 18 (1990)
129
Putschar, W. G. J.: Aggressives juveniles ossifizierendes Fibrom der linken Mandibula. Verb. dt. Ges. Path. 58 (1974) 251 Reaume, C. E., IL W. Schmid, R. K. Wesley: Aggressive ossifying fibroma of the mandible. J. Oral Maxillofac. Surg. 43 (1985) 631 Reed, R. J., D. M. Hagy: Benign nonodontogenic fibro-osseous lesions of the skull. Report of two cases. Oral Surg. 19 (1965) 214 Scharffetter, K., K. Kopf, Ch. Mittermayer: Dreidimensionale Rekonstruktion eines juvenilen ossifizierenden Fibroms. Dtsch. Z. Mund-Kiefer-Gesichts-Chir. 10 (1986) 252 Smith, A. G., A. Zavaleta: Osteoma, ossifying fibroma and fibrous dysplasia of facial and cranial bones. Arch. Pathol. 54 (1952) 507 Test III D., C. Schow, D. Cohen, H. TiIson: Case 17, part 2. Juvenile ossifying fibroma. J. Oral Surg. 34 (1976) 907 Waldron, C. A.: Fibro-osseous lesions of the jaws. J. Oral Maxillofac. Surg. 43 (1985) 249 Walter, J. M., B. C. Terry, E. W. Small, S. R. Matteson, R. M. Howell: Aggressive ossifying fibroma of the maxilla: review of the literature and report of case. J. Oral Surg. 37 (1979) 276
P. J. Slootweg M.D., D.M.D. Dept. of Pathology, UniversityHospital Heidelberglaan 100 Postbus 85500 NL-3508 GA Utrecht The Netherlands
125
Summary The present investigation concerns 4 patients with juvenile ossifying fibroma (JOF) whose data are analyzed together with 30 cases from the literature. The tumour mainly occurs in juveniles, 79 % of the patients being 15 years or younger. Radiologically as well as at surgery, the lesion is demarcated from its surroundings. Histologically, JOF is unique in showing a loose-fibroblastic stroma that contains garlandlike strands of osteoid with entrapped osteoblasts, the latter feature not being observed in other fibro-osseous lesions. JOF responds very well to conservative treatment that provided permanent cure in all cases with adequate follow-up data.
Juvenile Ossifying Fibroma Report of Four Cases Pieter J. Slootweg ~, Hellmuth Miiller 2 1Institute of Pathology(Head: Prof. J. A. M. van Unnik, M.D.), University of Utrecht zClinic for Maxillofacial Surgery(Head:Dr. H. Mfiller,M.D., D.M.D.), University Hospital Utrecht, The Netherlands Submitted 3.7. 1989; accepted 29.8. 1989
Key words Fibro-osseous lesion - Juvenile ossifying fibroma Jaw tumours
Introduction The group of fibro-osseous lesions of the maxillofacial skeleton includes an ill-defined entity known under a plethora of designations: young ossifying fibroma (Smith and Zavaleta, 1952; Fu and Perzin, 1974), juvenile ossifying fibroma (Reed and Hagy, 1965; Pindborg and HjortingHansen 1974; Test et al., 1976; Scharffetter et al., 1986), active juvenile ossifying fibroma (Waldron, 1985; Hoffman et al., 1987), aggressive ossifying fibroma (Walter et al., 1979; Reaume et al., 1985), juvenile aggressive ossifying fibroma (Putschar, 1974; Eversole et al., 1985) and trabecular desmo-osteoblastoma (Makek, 1983). Reports concerning this lesion are usually limited to single cases and with one exception (Makek, 1983) there have been no series from which data on clinical behaviour and histological spectrum can be inferred. Therefore, we considered it useful to report our experience with this lesion for which we employ the provisional designation "juvenile ossifying fibroma" (JOF).
Results Data on age, sex and location of the cases from the literature are presented in Table 1. Comparable data on our own cases are presented in Table 2 together with data on treatment and follow-up. All cases had swelling as the presenting symptom (Fig. 1), Case 1 had been seen for the first time in 1952 but for technical reasons definitive treatment was postponed until 7 years later, a time span during which the tumour had gradually increased in size. Radiographs were available of cases 1-3. Cases i and 3
Materials and Methods
Table I
Cases of juvenile ossifying fibroma from the literature
All benign fibro-osseous lesions presenting through the Oral Pathology Department of t h e Utrecht University were reviewed and 4 were considered to represent cases of JOF on the basis of clinical evidence of t u m o u r and histopathological features compatible with that diagnosis as they were provisionally defined, using reported data. These features include a cell-rich fibroblastic stroma, occasionally exhibiting a storiform pattern and highly cellular cords of osteoblasts appearing to be incorporated in osteoid (Pindborg and Hjerting-Hansen, 1974; Waldron, 1985). The data were extended by including cases from the literature that were reported under one of the designations mentioned in the introduction and by including cases not reported as JOF but warranting that diagnosis by their histopathological features as presented and illustrated in case reports (Dehner, 1973; Adekeye et al., 1980; Krumholz et al., 1986). The histological findings of JOF were compared with those encountered in 11 cases of radiologically, clinically and histologically well-demarcated fibro-osseous lesions representing ossifying fibroma (OF) conforming to established criteria (Eversole et al., 1985).
Mean age in years
Male/female
Location
12.2
19/11
maxilla 16 mandible 13 ethmoid 1
Table2
Present cases of juvenile ossifying fibroma
Case Sex
Age*
Location
Treatment
Follow-up
10 9 3 12
maxilla mandible maxilla maxilla
resection enucleation enucleation enucleation
NED** after 30 years NED after 5 years NED after 13 years recurrence after 3.5 and 10 years thereafter NED after 22 years
no.
1 2 3 4
F F M F
* in years ** No evidence of disease
126
J. Cranio-Max.-Fac. Surg. 18 (1990)
Fig. 1 Case 1. Tumour causes considerable deformity of the left side of the face, Appearance at time of surgical treatment after 7 years of clinical observation,
P. J. Slootweg, H. Miiller
Fig. 2 Case 1. Radiograph in a cranio-caudal direction shows expansion of the left maxilla. The lesion is mixed radiodense-radiolucent and the cortical bone is visible as a demarcated radiodense line.
Fig.3 Case 2. Radiograph shows expansion of the left mandibular ramus due to a lesion with a ground glass appearance. Bordering cortical bone is observed as a distinct radiodense line,
were mixed radiolucent-radiopaque with vaguely outlined radiodense areas (Fig. 2) and case 2 exhibited a mildly radiopaque homogeneous appearance mimicking a ground glass pattern (Fig. 3). From case 4, radiographs were available of the lesion when initially seen and at the time of operation, 7 years later. During that time, the lesion had become more radiodense. All lesions were well circumscribed without blending into the normal surrounding bone and an expanded cortical layer could be discerned as a radiodense line bordering the lesion (Fig. 2). Histologically, all four cases were
characterized by the presence of loose fibrous tissue with spindle-shaped fibroblasts exhibiting ovoid nuclei with finely granular chromatin. Mitotic figures were present in all lesions although their number varied among individual cases. In all lesions, there were focal collections of multinucleated giant cells, mostly in areas of cystic degeneration, oedema and haemorrhage but also unrelated to these stromal alterations. All lesions exhibited bone formation as follows. There were focal aggregates of large plump eosinophilic cells resembling osteoblasts that appeared to be incorporated in a
Juvenile Ossifying Fibroma
J. Cranio-Max.-Fac. Surg. 18 (1990)
12 7
Fig.4 Photomicrograph shows typical appearance of JOF consisting of strands of osteoid with entrapped cells in a loose fibrillary background tissue (HE x 75).
Fig. 5 The strands of osteoid are irregularly mineralized and bordered by osteoblasts (HE x 120),
Fig. 6 Sometimes the osteoblastic rimming of woven bone trabeculae may be very prominent. Osteoclasts are also present at the border of the bone (HE x 75)
Fig. 7 The bony component may increase to a proportionally large size together with decreased cellularity of the stroma. The woven nature of the bone is nevertheless retained (HE x 75).
dense-fibrillary osteoid m a t r i x that surrounded them. These areas of osteoid with e n t r a p p e d cells fused to f o r m anastomosing cords that merged with irregularly calcified trabeculae of woven bone rimmed by p l u m p osteoblasts and osteoclasts (Figs. 4-6). Lamellar bone was not observed. In cases 1 and 4 tissue was removed on several occasions over a time span of 6 to 10 years. In these cases, a kind of
m a t u r a t i o n was observed, in the sense that there were stromal areas with a decreased cellularity where the cells were surrounded by a fine-fibrillar, pale-staining collagenous matrix. In both cases, this p a t t e r n was not observed at the time of inital presentation. M o r e o v e r the b o n y component had p r o p o r t i o n a l l y g r o w n larger and the b o n y trabeculae were coarse and had sometimes coalesced to areas with little intervening stroma remaining (Fig. 7), but the
128
]. Cranio-Max.-Fac.Surg. 18 (1990)
Table3
Present cases of ossifying fibroma
Mean age in years
Male/female
Location
25.1
7/4
maxilla 4 mandible 6 ethmoid 1
bony component had retained its woven nature, maturation towards lamellar bone being absent. In all cases, the available slides permitted evaluation of the boundary between tumour and surrounding jaw bone; the lesion was circumscribed and there was no blending of the lesional bone with the expanded cortical layer or the medullary bone spongiosa. An apparent fibrous capsule was, however, lacking in all cases, the tumour stroma being in immediate contact with the surrounding jaw bone. Histological examination of the 11 OF cases showed these to have a rather varying appearance; stroma varied from hyaline or fibrous to cellular and the mineralized material included woven bone, lamellar bone, spheroid basophilic particles that were interpreted as cementicles and smoothly contoured, curvilinear, cell-poor trabeculae. Woven bone was the only feature common to OF as well as JOF. Clinical data of the 11 OF cases are shown in Table 3. Discussion The data from the literature and the present cases lead to the following conclusions on JOF. Age distribution and mean age of the cases warrant the adjective juvenile; only 21% of the patients is older than 15 years. A site of predilection is not apparently present, upper and lower jaw being almost equally involved; extragnathic cases are rare. The presenting clinical symptom is swelling. The growth rate is variable, case 2 exhibited a rapid growth whereas cases 1 and 4 steadily increased in size. The radiological features are variable. Depending on the extent of ossification, the uni- or multilocular lesion may be radiolucent or mixed radiolucent-radiodense but there is always a distinct radiodense border. Our case 1 serves to illustrate that an initially radiolucent lesion may become more radiodense when left in situ. Lesions have been reported to be removed by radical resection (Smith and Zavaleta, 1952; Putschar, 1974) or in a conservative way by local excision or enucleation with subsequent curettage (Smith and Zavaleta, 1952; Fu and Perzin, 1974; Test et al., 1976; Makek, 1983; Reaume et al., 1985). Data from the literature as well as our own follow-up data (Table 2) indicate that all patients have been cured of their tumour although some required two or more surgical attempts because of recurrent turnout. As there is no difference in outcome between patients treated in a more limited way and those treated by major surgery, it seems appropriate to recommend a conservative surgical approach when managing JOF. The present data do not support the assumption that JOF may be locally invasive and may be fatal (Reed and Hagy, 1965). Moreover, we have not been able to trace any documented report of a case of JOF transforming into osteosarcoma, a possibility mentioned in discussions on JOF (Hoffman et al., 1987). Concerning the histomorphology, data from the literature
P.J. Slootweg, H. Mi~ller and the present cases allow the following outlines to be drawn. The tumour is composed of a loose fibrilar stroma containing numerous fibroblasts. The fibroblasts have vesicular nuclei and predominant nucleoli indicating their very active nature. Mitoses are present but are not very numerous. Throughout the fibrous stroma there are garland-like strands of osteoblasts with interspersed osteoid that are continuous with trabeculae of woven bone with an osteoblastic rim. The stroma may exhibit areas of haemorrhage and cystic degeneration and preferably in these parts, osteoclast-like giant cells may be very numerous. Histologically, the lesion is well demarcated from its surroundings. The tumour does not show a great propensity to maturation, defined as progression towards an end-stage in which the lesion exclusively consists of calcified material. In our cases 1 and 4 who yielded material for histological investigation on several occasions, cell-rich stroma remained identifiable throughout the whole time and none of the available reports mentioned a substantial alteration in tumour morphology related to duration of symptoms. Whether the tumour exhibits maturation from woven towards lamellar bone is uncertain. Presence of lamellar bone is sometimes reported (Reed and Hagy, 1965) but not mentioned to be present by others (Putschar, 1974; Walter et al., 1979; Makek, 1983; Hoffman et al., 1987) and nor was it observed by us. H o w is JOF to be distinguished from other fibro-osseous jaw lesions? The clinical and radiological demarcation between the lesion and the surrounding tissue preclude considering JOF as a variant of fibrous dysplasia as this latter lesion typically blends imperceptibly into the adjacent bone (Waldron, 1985). As far as histology is concerned, JOF can be distinguished from fibrous dysplasia by the very prominent osteoblastic rimming of the bony trabeculae and by the demarcation between lesional bone and adjacent jaw bone provided that surrounding tissue is included in the biopsy specimen. Thus, clinical, radiological and histological characteristics are different and speak against considering JOF a variant of fibrous dysplasia (Adekeye et al., 1980). Moreover, the continuous growth that is shown by JOF refutes a dysplastic nature and makes it more appropriate to consider JOF a neoplasm. The next question is whether there is any reason to distinguish between JOF and OF. Clinical, radiological and histological characteristics agree, as in both they point towards a sharp delineation between turnout and surrounding tissue. There are, however, diverging features warranting separation of JOF from OF. JOF occurs at a far lower mean age than OF: 8.5 years as opposed to 25.1 years in our own OF cases and 36 years in another OF series (Eversole et al., 1985). Moreover, OF contains lamellar bone and cementicles as well as smoothly contoured, cell-poor, curvilinear trabeculae; features that are absent in JOF whereas the osteoblastic cords and the loose, active-appearing fibrous stroma that characterize JOF are absent in OF. It appears that histomorphology is specific enough to make separate categorization of JOF and OF possible. We conclude that within the group of craniofacial fibroosseous lesions, JOF is an entity in its own right: histologically unique in showing highly cellular garland-like strands with entrapped osteoblasts, radiologically, clinically and histologically well-demarcated from its surroundings and amenable to conservative treatment.
Juvenile Ossifying Fibrorna References
Adekeye, E. 0., M. B. Edwards, G. E. Goubran: Fibro-osseous lesions of the skull, face and jaws in Kaduna, Nigeria. Br. J. Oral Surg. 18 (1980) 57 Dehner, L. P.: Tumors of the mandible and maxilla in children. I. Clinicopathologic study of 46 histologically benign lesions. Cancer 31 (1973) 364 Eversole, L. R., A. S. Leider, K. Nelson: Ossifying fibroma: a clinicopathologic study of sixty-four cases. Oral Surg. 60 (1985) 505 Fu, Y. S., K. H. Perzin: Non-epithelial tumors of the nasal cavity, paranasal sinuses, and nasopharynx: a clinico-pathologic study. II. Osseous and fibro-osseous lesions, including osteoma, fibrous dysplasia, ossifying fibroma, osteoblastoma, giant cell tumor, and osteosarcoma. Cancer 33 (1974) 1289 Hoffman, S., J. R. Jacoway, S. O. KrolIs: Intraosseous and parosteal tumors of the jaws. Atlas of tumor pathology, 2th series, fascicle 24. Armed Forces Institute of Pathology, Washington (1987) 208 Krumholz, K., E. Kri~ger, G. Kn~pfle: Verlaufsform des zentralen Fibroms. In: Fortschritte der Kiefer- und Gesichtschirurgie, ein Jahrbuch. Band XXXI. Knochentumoren und Systemerkrankungen im Kiefer-Gesichtsbereich. Thieme, Stuttgart (1986) 25 Makek, M.: Clinical pathology of fibro-osteo-cemental lesions in the cranio-facial and jaw bones. A new approach to differential diagnosis. Karger, Basel (1983) 162 Pindborg, J. J., E. Hj~rting-Hansen: Atlas of diseases of the jaws. Munksgaard, Copenhagen (1974) 68
J. Cranio-Max.-Fac. Surg. 18 (1990)
129
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P. J. Slootweg M.D., D.M.D. Dept. of Pathology, UniversityHospital Heidelberglaan 100 Postbus 85500 NL-3508 GA Utrecht The Netherlands