Pediatr Radiol (1991) 21:449-451
Pediatric Radiology 9 Springer-Verlag 1991
Congenital ossifying fibroma (osteofibrous dysplasia) of the tibiaa case report N. M. Smith 1, R. W. Byard ~, B. Foster 2, L. Morris 3, B. Clark 3 and A. J. B o u r n e s Departments of 1 Histopathology, 2 Orthopaedic Surgeryand 3 Radiology, Adelaide Children's Hospital, North Adelaide, South Australia, Australia Received: 27 November 1990; accepted: 18 February 1991
Abstract. Ossifying fibromas of the long bones of the leg are benign lesions occurring in the pediatric age group identical in histological a p p e a r a n c e to the similarly n a m e d tumor o f t h e j a w i n adults. Most frequently p r e s e n t a t i o n occurs after minor t r a u m a with symptoms of a swelling of the tibia or fibula which m a y be painful. Pathological fracture or limp are also occasional presentations. Congenital cases are extremely rare. We describe an otherwise normal male n e o n a t e who presented at birth with a b o w e d right lower leg. The limb was 1 cm shorter than the other side, with tibia vara and a firm mass situated anteriorly. X-ray showed a mixed lytic and sclerotic lesion in the proximal metaphysis of the tibia. Biopsy showed collagenous stroma containing spindle cells and irregular trabeculae of woven bone r i m m e d by p l u m p osteoblasts. A s the appearances were typical of an ossifying fibroma (osteofibrous dysplasia) no surgical t r e a t m e n t was given. The patient was well with no growth of the t u m o r and with radiological evidence of healing at 1 year follow up. This case is p r e s e n t e d to draw attention to the clinicopathological features of this unusuallesion which must be considered in the differential diagnosis of congenital lesions of the tibia.
Ossifying fibroma of long bones was first characterised as a distinct entity in 1966, in an account of two cases of a tibial t u m o r which r e s e m b l e d the well described, similarly-named lesion of the jaw [1]. Subsequent authors have p r e f e r r e d the terms osteofibrous dysplasia [2] ( O . E D . ) or intracortical fibrous dysplasia [3], although use of the latter
term should be discouraged because fibrous dysplasia is a m e d u l l a r y lesion [4,51. T h e entity is considered to be a disorder of childhood and adolescence [6] though in the literature the age at presentation varies b e t w e e n seven days and twenty two years [1, 4-12]. We describe a case of congenital ossifying fibroma occurring in the tibia of a n e o n a t e and discuss the clinical, radiological, pathological and prognostic features of the entity.
Clinical history A male infant was born at 41 weeks gestation after an uneventful pregnancy. Lower segment cesarean section was performed due to brow presentation. The birth weight was 4.3 kg. Physical examination was unremarkable except for the right lower leg which was
shortened by 1 cm, with varus displacement and a firm tibial mass anteriorly. Two siblings were alive and well. There was no history of parental abnormality or consanguinity. Chromosome studies revealed a normal XY karyotype.
Radiology Plain x-rays revealed a mixed lytic and sclerotic lesion in the proximal metaphysis of the right tibia (Figs. I a, b). Bone scan showed increased trace uptake in the proximal 2/3 of the tibia with an otherwise normal skeleton (Fig. 2). Biopsy, preserving the proximal tibial epiphysis, was performed at twelve days of age. No surgical treatment was given following this. Subsequent x-rays over four months showed deposition of periosteal new bone and at twelve months, consolidation of new bone in the diaphysis (Figs. 3 a, b), associated with persistent antero-posterior bowing and varus deformity of the tibia.
Histopathology
Fig.la, b. X-rays taken at 15 days of age showing a mixed lytic and sclerotic lesion in the proximal metaphysis of the right tibia, a postero-anterior, b lateral
A portion of white, firm tissue measuring 20 x 8 x 3 mm was received. Bony elements were apparent macroscopically. The entire specimen was processed for paraffin embedding and hematoxylin and eosin staining. Microscopy, showed sheets of interwoven plump spindle cells separated by bands of collagen. In areas of increased cellularity occasional normal mitoses were present. Spindle cell nuclei were enlarged but no hyperchromatism was present. Within the stroma there were irregularly shaped trabeculae of woven bone, most of which were rimmed by plump osteoblasts (Fig. 4). Occasional osteoclasts were present. Toward the periphery of the lesion reactive lamella bone was apparent beneath thickened periosteum. The appearances were typical of an ossifying fibroma.
N. M. Smith et al.: Congenital ossifying fibroma
450 Discussion
Fig. 2. Bone scan at 10 days of age showingincreased uptake of tracer material in proximal 2/3of tibia
Fig.3a, b. X-rays taken 12 months after birth showing consolidation of new bone in the diaphysis and deposition of periosteal bone, a postero-anterior, b lateral
The first report of ossifying fibroma was that of Frangenheim (quoted by Campanacci and Marks et al.) who described what he thought was a congenital osteitis fibrosa of the tibia in 1921 [2, 13]. Kempson and Campanacci subsequently reported cases of the lesion in the long bones of children, which contrasted with the more common site of the mandible of adults [1, 2,13]. The age range in the literature is seven days to 22 years with neonatal cases being exceedingly rare. The reported case demonstrates however, that the lesions can occur at birth and should, therefore, be included in the differential diagnosis of congenital bone lesions. The clinical presentation in children most often occurs after minor trauma and is usually marked by swelling or bowing of the tibia or fibula, sometimes with pain. Occasionally pathological fracture occurs, and in some cases a limp may be the initial complaint [1, 4-12]. Rarely, both tibia and fibula of the same limb may be affected [7, 13]. There is no clear sex predilection [1,4-12]. Radiological examination most often reveals an eccentric intracortical lytic lesionin the diaphysis or metaphysis with a rim of reactive bone, cortical expansion, and bowing of the bone in the anteroposterior direction [4]. Bone scan shows intense isotope uptake [10, 13], and vascular proliferation is seen on angiography [13]. The differential diagnosis in infants and children includes fibrous dysplasia, which uncommonly origin-
Fig.4. Irregular trabeculae of woven bone rimmed by osteoblasts from the biopsy taken at 12 days of age (Hematoxylin and eosin, original magnification x 130)
ates in the cortex, non ossifying fibroma and adamantinoma [5, 13]. In the neonate, congenital aneurysmal bone cyst and pseudarthrosis due to neurofibromatosis need to be considered and, though very rare, congenital fibrous histiocytoma, eosinophilic granuloma, fibromatosis, myofibromatosis, and malignant fibrous histiocytoma need to be excluded [14]. Solitary metastasis from other congenital tumors such as neuroblastoma may occur. Another lesion causing tibia vara is fibrocartilaginous dysplasia, thought to represent abnormal development of fibrocartilage at the insertion of the tendinous expansions of the sartorius, gracilis and semitendinosus muscles [15]. Chronic osteomyelitis should also be considered [12]. Distinction of ossifying fibroma (or O.ED.) from fibrous dysplasia, the monostotic form of which is rarely progressive, depends upon the demonstration of osteoblastic rimming of bone trabeculae, some of which may be composed of lamella rather than of woven bone [5, 9]. Adamantinoma, a lesion seen in the pediatric group, though unusual before the age of 10 years, has a similar radiological appearance and anatomical location, but may be differentiated by the presence of cytokeratin positive epithelial elements [7, 8, 16]. Non ossifying fibroma rarely has a bony component [11]. Aneurysmal bone cyst usually includes giant cells, hemosiderin deposition and blood filled spaces and though osteoid may be present, does not usually have well defined bony islands, unless associated with degeneration of an underlying bone-producing tumor [14]. In congenital pseudarthrosis due to neurofibromatosis other manifestations of the disease are not always present and there may be incorporation of islands of bone. The focal myxoid quality of the otherwise densely collagenous fibrous stroma in con genital pseudarthrosis may be helpful in arriving at the correct diagnosis [17]. Congenital histiocytosis X or eosinophilic granuloma rarely affects the tibia or fibula, showing a predilection for the skull, femur, pelvic bones and ribs [14]. Fibrous histiocytoma and myofibromatosis do not usually produce bone in the stroma. Malignant fibrous histiocytoma invariably destroys adjacent bone and has a pleomorphic stroma. Choice of treatment of ossifying fibroma (or O.F.D.) is tempered by reports of limited progression and even of spontaneous regression [2, 8, 12, 16, 18] and a variably conservative approach has been recommended [6]. Different authors have suggested various surgical policies [2, 7, 11]. If surgery is indicated,
N. M. Smith et al.: Congenital ossifying fibroma for instance where there is a high risk of pathological fracture, wide local excision has been found to reduce the risk of local recurrence which occurs after curettage [10-13,19]. There is no place for radiotherapy and chemotherapy in treatment [13]. The clinical course of our patient supports limited intervention, in that he is well following biopsy with radiological studies indicating that the lesion continues to regress 12 months after diagnosis. The relationship between adamantinoma and ossifying fibroma, two tumors with remarkably similar clinical and radiological features has been examined [5, 16]. The suggestion that ossifying fibroma represents the regression phase of adamantinoma should lead pathologists to search for features of both lesions in each new case. Even if such a relationship was establish ed, however, the possibility of ossifying fibroma arising as a de novo entity could not be definitely excluded [16]. In conclusion, we have presented the clinicopathological features of this rare benign tumor to emphasize that it may occur at a very young age and should, therefore, be considered in cases of congenital bone tumors of the lower limbs. Surgical intervention is indicated only under certain conditions, as spontaneous healing may occur. Acknowledgements. The authors would like
to thank S. Duncan for excellent secretarial work in typing the manuscript.
451
References 1. Kempson RL (1966) Ossifying fibroma of the long bones. Arch Pathot 82:218 2. Campanacci M (1976) Osteofibrous dysplasia of long bones. A new clinical entity. Ital J Orthop Traumatol 2: 22I 3. Johnson LC (1972) Congenital pseudarthosis, adamantinoma of long bones and intracortical fibrous dysplasia of the tibia. J Bone Joint Surg (Am) 54A: 1355 4. Capusten BM, Rochon L, Rosman MA, Marton D (1980) Osteofibrous dysplasia. J Can Assoc Radio131: 50 5. Markel SF (1978) Ossifying fibroma of Iong bone. Its distinction from fibrous dysplasia and its association with adamantinoma of long bone. Am J Clin Patho169: 91 6. Blackwell JB, McCarthy SW, Xipell JM, Vernon Roberts B, Duhig RET (1988) Osteofibrous dysplasia of the tibia and fibula. Pathology 20:227 7. Campanacci M, Laus M (t981) Osteofibrous dysplasia of the tibia and fibula. J Bone Joint Surg (Am) 63A: 367 8. Campbell CJ, Hawk T (1982) A variant of fibrous dysplasia (Osteofibrous dysplasia). J Bone Joint Surg (Am) 64A: 231 9. Goergen TG, Dickman PS, Resnick D, Saltzstein SL, O'Dell CW, Akeson WH (1977) Long bone ossifying fibromas. Cancer 39:2067 10. Macintosh D, Xipell JM, Thomas DP (1986) Ossifying fibroma of long bone report of two cases. Aust Radiol 30:124 11. Nakashima Y, Yamamuro T, Fujiwara Y, Kotoura Y, Mori E, Hamashima Y (1983) Osteofibrous dysplasia (Ossifying fibroma of long bones). A study of twelve cases. Cancer 52:909
12. Castellote A, Garcia-Pena R Lucaya J, Lorenzo J (1988) Osteofibrous dysplasia. Skeletal Radiol 17:483 13. Marks KE, Bauer TW (1989) Fibrous tumors of bone. Orth ClinNorthAm 20:377 14. Dehner LP (1987) Pediatric surgical pathology. Williams & Wilkins, Baltimore, p 939 15. Bell SN, Campbell PF, Cole WG, Menelaus MB (1985) Tibia vara caused by focal fibrocartilaginous dysplasia. J Bone Joint Surg (Br) 67B: 780 16. Czerniak B, Rojas-Corona RR, Dorfman H (1989) Morphologic diversity of long bone adamantinoma. The concept of differentiated (regressing) adamantinoma and its relationship to osteofibrous dysplasia. Cancer 64:2319 17. Boyd HB, Sage RP (1958) Congenital pseudarthrosis of the tibia. J Bone Joint Surg (Am) 40A: 1245 18. Spjut HJ, Ayala AG (1986) Skeletal tumors in childhood at~d adolescence. In: Finegold M (ed) Pathologyof neoptasia in children and adolescents. WB Saunders, Philadelphia, p 256 19. Schoenecker PL, Swanson K, Sheridan JJ (1981) Ossifying fibroma of the tibia. Report of a new case and review of the literature. J Bone Joint Surg (Am) 63A: 483
Dr- R. W. Byard Histopathology Department The Adelaide Children's Hospital King William Road North Adelaide, South Australia 5006 Australia
Pediatric Radiology 9 Springer-Verlag 1991
Congenital ossifying fibroma (osteofibrous dysplasia) of the tibiaa case report N. M. Smith 1, R. W. Byard ~, B. Foster 2, L. Morris 3, B. Clark 3 and A. J. B o u r n e s Departments of 1 Histopathology, 2 Orthopaedic Surgeryand 3 Radiology, Adelaide Children's Hospital, North Adelaide, South Australia, Australia Received: 27 November 1990; accepted: 18 February 1991
Abstract. Ossifying fibromas of the long bones of the leg are benign lesions occurring in the pediatric age group identical in histological a p p e a r a n c e to the similarly n a m e d tumor o f t h e j a w i n adults. Most frequently p r e s e n t a t i o n occurs after minor t r a u m a with symptoms of a swelling of the tibia or fibula which m a y be painful. Pathological fracture or limp are also occasional presentations. Congenital cases are extremely rare. We describe an otherwise normal male n e o n a t e who presented at birth with a b o w e d right lower leg. The limb was 1 cm shorter than the other side, with tibia vara and a firm mass situated anteriorly. X-ray showed a mixed lytic and sclerotic lesion in the proximal metaphysis of the tibia. Biopsy showed collagenous stroma containing spindle cells and irregular trabeculae of woven bone r i m m e d by p l u m p osteoblasts. A s the appearances were typical of an ossifying fibroma (osteofibrous dysplasia) no surgical t r e a t m e n t was given. The patient was well with no growth of the t u m o r and with radiological evidence of healing at 1 year follow up. This case is p r e s e n t e d to draw attention to the clinicopathological features of this unusuallesion which must be considered in the differential diagnosis of congenital lesions of the tibia.
Ossifying fibroma of long bones was first characterised as a distinct entity in 1966, in an account of two cases of a tibial t u m o r which r e s e m b l e d the well described, similarly-named lesion of the jaw [1]. Subsequent authors have p r e f e r r e d the terms osteofibrous dysplasia [2] ( O . E D . ) or intracortical fibrous dysplasia [3], although use of the latter
term should be discouraged because fibrous dysplasia is a m e d u l l a r y lesion [4,51. T h e entity is considered to be a disorder of childhood and adolescence [6] though in the literature the age at presentation varies b e t w e e n seven days and twenty two years [1, 4-12]. We describe a case of congenital ossifying fibroma occurring in the tibia of a n e o n a t e and discuss the clinical, radiological, pathological and prognostic features of the entity.
Clinical history A male infant was born at 41 weeks gestation after an uneventful pregnancy. Lower segment cesarean section was performed due to brow presentation. The birth weight was 4.3 kg. Physical examination was unremarkable except for the right lower leg which was
shortened by 1 cm, with varus displacement and a firm tibial mass anteriorly. Two siblings were alive and well. There was no history of parental abnormality or consanguinity. Chromosome studies revealed a normal XY karyotype.
Radiology Plain x-rays revealed a mixed lytic and sclerotic lesion in the proximal metaphysis of the right tibia (Figs. I a, b). Bone scan showed increased trace uptake in the proximal 2/3 of the tibia with an otherwise normal skeleton (Fig. 2). Biopsy, preserving the proximal tibial epiphysis, was performed at twelve days of age. No surgical treatment was given following this. Subsequent x-rays over four months showed deposition of periosteal new bone and at twelve months, consolidation of new bone in the diaphysis (Figs. 3 a, b), associated with persistent antero-posterior bowing and varus deformity of the tibia.
Histopathology
Fig.la, b. X-rays taken at 15 days of age showing a mixed lytic and sclerotic lesion in the proximal metaphysis of the right tibia, a postero-anterior, b lateral
A portion of white, firm tissue measuring 20 x 8 x 3 mm was received. Bony elements were apparent macroscopically. The entire specimen was processed for paraffin embedding and hematoxylin and eosin staining. Microscopy, showed sheets of interwoven plump spindle cells separated by bands of collagen. In areas of increased cellularity occasional normal mitoses were present. Spindle cell nuclei were enlarged but no hyperchromatism was present. Within the stroma there were irregularly shaped trabeculae of woven bone, most of which were rimmed by plump osteoblasts (Fig. 4). Occasional osteoclasts were present. Toward the periphery of the lesion reactive lamella bone was apparent beneath thickened periosteum. The appearances were typical of an ossifying fibroma.
N. M. Smith et al.: Congenital ossifying fibroma
450 Discussion
Fig. 2. Bone scan at 10 days of age showingincreased uptake of tracer material in proximal 2/3of tibia
Fig.3a, b. X-rays taken 12 months after birth showing consolidation of new bone in the diaphysis and deposition of periosteal bone, a postero-anterior, b lateral
The first report of ossifying fibroma was that of Frangenheim (quoted by Campanacci and Marks et al.) who described what he thought was a congenital osteitis fibrosa of the tibia in 1921 [2, 13]. Kempson and Campanacci subsequently reported cases of the lesion in the long bones of children, which contrasted with the more common site of the mandible of adults [1, 2,13]. The age range in the literature is seven days to 22 years with neonatal cases being exceedingly rare. The reported case demonstrates however, that the lesions can occur at birth and should, therefore, be included in the differential diagnosis of congenital bone lesions. The clinical presentation in children most often occurs after minor trauma and is usually marked by swelling or bowing of the tibia or fibula, sometimes with pain. Occasionally pathological fracture occurs, and in some cases a limp may be the initial complaint [1, 4-12]. Rarely, both tibia and fibula of the same limb may be affected [7, 13]. There is no clear sex predilection [1,4-12]. Radiological examination most often reveals an eccentric intracortical lytic lesionin the diaphysis or metaphysis with a rim of reactive bone, cortical expansion, and bowing of the bone in the anteroposterior direction [4]. Bone scan shows intense isotope uptake [10, 13], and vascular proliferation is seen on angiography [13]. The differential diagnosis in infants and children includes fibrous dysplasia, which uncommonly origin-
Fig.4. Irregular trabeculae of woven bone rimmed by osteoblasts from the biopsy taken at 12 days of age (Hematoxylin and eosin, original magnification x 130)
ates in the cortex, non ossifying fibroma and adamantinoma [5, 13]. In the neonate, congenital aneurysmal bone cyst and pseudarthrosis due to neurofibromatosis need to be considered and, though very rare, congenital fibrous histiocytoma, eosinophilic granuloma, fibromatosis, myofibromatosis, and malignant fibrous histiocytoma need to be excluded [14]. Solitary metastasis from other congenital tumors such as neuroblastoma may occur. Another lesion causing tibia vara is fibrocartilaginous dysplasia, thought to represent abnormal development of fibrocartilage at the insertion of the tendinous expansions of the sartorius, gracilis and semitendinosus muscles [15]. Chronic osteomyelitis should also be considered [12]. Distinction of ossifying fibroma (or O.ED.) from fibrous dysplasia, the monostotic form of which is rarely progressive, depends upon the demonstration of osteoblastic rimming of bone trabeculae, some of which may be composed of lamella rather than of woven bone [5, 9]. Adamantinoma, a lesion seen in the pediatric group, though unusual before the age of 10 years, has a similar radiological appearance and anatomical location, but may be differentiated by the presence of cytokeratin positive epithelial elements [7, 8, 16]. Non ossifying fibroma rarely has a bony component [11]. Aneurysmal bone cyst usually includes giant cells, hemosiderin deposition and blood filled spaces and though osteoid may be present, does not usually have well defined bony islands, unless associated with degeneration of an underlying bone-producing tumor [14]. In congenital pseudarthrosis due to neurofibromatosis other manifestations of the disease are not always present and there may be incorporation of islands of bone. The focal myxoid quality of the otherwise densely collagenous fibrous stroma in con genital pseudarthrosis may be helpful in arriving at the correct diagnosis [17]. Congenital histiocytosis X or eosinophilic granuloma rarely affects the tibia or fibula, showing a predilection for the skull, femur, pelvic bones and ribs [14]. Fibrous histiocytoma and myofibromatosis do not usually produce bone in the stroma. Malignant fibrous histiocytoma invariably destroys adjacent bone and has a pleomorphic stroma. Choice of treatment of ossifying fibroma (or O.F.D.) is tempered by reports of limited progression and even of spontaneous regression [2, 8, 12, 16, 18] and a variably conservative approach has been recommended [6]. Different authors have suggested various surgical policies [2, 7, 11]. If surgery is indicated,
N. M. Smith et al.: Congenital ossifying fibroma for instance where there is a high risk of pathological fracture, wide local excision has been found to reduce the risk of local recurrence which occurs after curettage [10-13,19]. There is no place for radiotherapy and chemotherapy in treatment [13]. The clinical course of our patient supports limited intervention, in that he is well following biopsy with radiological studies indicating that the lesion continues to regress 12 months after diagnosis. The relationship between adamantinoma and ossifying fibroma, two tumors with remarkably similar clinical and radiological features has been examined [5, 16]. The suggestion that ossifying fibroma represents the regression phase of adamantinoma should lead pathologists to search for features of both lesions in each new case. Even if such a relationship was establish ed, however, the possibility of ossifying fibroma arising as a de novo entity could not be definitely excluded [16]. In conclusion, we have presented the clinicopathological features of this rare benign tumor to emphasize that it may occur at a very young age and should, therefore, be considered in cases of congenital bone tumors of the lower limbs. Surgical intervention is indicated only under certain conditions, as spontaneous healing may occur. Acknowledgements. The authors would like
to thank S. Duncan for excellent secretarial work in typing the manuscript.
451
References 1. Kempson RL (1966) Ossifying fibroma of the long bones. Arch Pathot 82:218 2. Campanacci M (1976) Osteofibrous dysplasia of long bones. A new clinical entity. Ital J Orthop Traumatol 2: 22I 3. Johnson LC (1972) Congenital pseudarthosis, adamantinoma of long bones and intracortical fibrous dysplasia of the tibia. J Bone Joint Surg (Am) 54A: 1355 4. Capusten BM, Rochon L, Rosman MA, Marton D (1980) Osteofibrous dysplasia. J Can Assoc Radio131: 50 5. Markel SF (1978) Ossifying fibroma of Iong bone. Its distinction from fibrous dysplasia and its association with adamantinoma of long bone. Am J Clin Patho169: 91 6. Blackwell JB, McCarthy SW, Xipell JM, Vernon Roberts B, Duhig RET (1988) Osteofibrous dysplasia of the tibia and fibula. Pathology 20:227 7. Campanacci M, Laus M (t981) Osteofibrous dysplasia of the tibia and fibula. J Bone Joint Surg (Am) 63A: 367 8. Campbell CJ, Hawk T (1982) A variant of fibrous dysplasia (Osteofibrous dysplasia). J Bone Joint Surg (Am) 64A: 231 9. Goergen TG, Dickman PS, Resnick D, Saltzstein SL, O'Dell CW, Akeson WH (1977) Long bone ossifying fibromas. Cancer 39:2067 10. Macintosh D, Xipell JM, Thomas DP (1986) Ossifying fibroma of long bone report of two cases. Aust Radiol 30:124 11. Nakashima Y, Yamamuro T, Fujiwara Y, Kotoura Y, Mori E, Hamashima Y (1983) Osteofibrous dysplasia (Ossifying fibroma of long bones). A study of twelve cases. Cancer 52:909
12. Castellote A, Garcia-Pena R Lucaya J, Lorenzo J (1988) Osteofibrous dysplasia. Skeletal Radiol 17:483 13. Marks KE, Bauer TW (1989) Fibrous tumors of bone. Orth ClinNorthAm 20:377 14. Dehner LP (1987) Pediatric surgical pathology. Williams & Wilkins, Baltimore, p 939 15. Bell SN, Campbell PF, Cole WG, Menelaus MB (1985) Tibia vara caused by focal fibrocartilaginous dysplasia. J Bone Joint Surg (Br) 67B: 780 16. Czerniak B, Rojas-Corona RR, Dorfman H (1989) Morphologic diversity of long bone adamantinoma. The concept of differentiated (regressing) adamantinoma and its relationship to osteofibrous dysplasia. Cancer 64:2319 17. Boyd HB, Sage RP (1958) Congenital pseudarthrosis of the tibia. J Bone Joint Surg (Am) 40A: 1245 18. Spjut HJ, Ayala AG (1986) Skeletal tumors in childhood at~d adolescence. In: Finegold M (ed) Pathologyof neoptasia in children and adolescents. WB Saunders, Philadelphia, p 256 19. Schoenecker PL, Swanson K, Sheridan JJ (1981) Ossifying fibroma of the tibia. Report of a new case and review of the literature. J Bone Joint Surg (Am) 63A: 483
Dr- R. W. Byard Histopathology Department The Adelaide Children's Hospital King William Road North Adelaide, South Australia 5006 Australia
