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A rare aneurysmal bone cyst of the maxillary sinus: a case report
Auris Nasus Larynx 28 (2001) S131– S137 www.elsevier.com/locate/anl
A rare aneurysmal bone cyst of the maxillary sinus: a case report Fumiyuki Suzuki *, Satoshi Fukuda, Katsunori Yagi, Eiji Chida, Yukio Inuyama Department of Otolaryngology, Hokkaido Uni6ersity School of Medicine, kita 15 nishi 7, kita-ku, Sapporo, 060 -8638 Japan Received 5 January 2001; received in revised form 6 February 2001; accepted 8 February 2001
Abstract Aneurysmal bone cyst (ABC) is a non-neoplastic expansile bone lesion that is common in the long bones; only 2% occurs in the head and neck. We present a case of ABC in a 23-year-old male and describe the clinical and radiological features, histopathology and treatment. Magnetic resonance imaging (MRI) demonstrated multiple internal septations, cysts with fluid-fluid levels of varying intensity, and an intact rim of low-intensity signal completely surrounding the lesion. The tumor was removed by enucleation with resection of the lateral nasal cavity. Histopathologic diagnosis was ABC and fibrous dysplasia. We suggest that MRI is very useful for the diagnosis of ABC. ABC is thought to follow other lesions, and thus when treating ABC, it is important to determine whether any pre-existing lesion has preceded or not; in particular, if the lesion site is in the head and neck region. © 2001 Elsevier Science Ireland Ltd. All rights reserved. Keywords: Aneurysmal bone cyst; MRI; CT
1. Introduction Aneurysmal bone cyst (ABC) is a non-neoplastic bone lesion developing mainly in the long bones, which rarely occurs in the head and neck region. We have experienced a case of aneurysmal bone cyst developed in the maxillary sinus. We present the case and discuss the characteristics on imaging with some references to pertinent literature.
2. A case report Patient: a 23-year-old man. Chief complaint: swelling of the left cheek. Family history: nothing particular. Previous history: neither trauma in the face nor operation of paranasal sinus. There was nothing particular. Present history: since June 1996, he noticed swelling of the left cheek. As he had no pain, he left it. However, as the swelling gradually enlarged, he consulted a * Corresponding author. Tel.: + 81-11-7073387; fax: +81-117177566. E-mail address: [email protected] (F. Suzuki).
otolaryngologist nearby. Fine needle aspiration cytology was performed from the lesion and the cells of the lesion consisted of hematocyte only. Then, he was referred to our Department of Otolaryngology, Hokkaido University Hospital for further examination. Findings at the first visit; the left cheek was conspicuously swollen. The lesion was elastic hard on palpation. The skin surface of left cheek had no abnormality and maintained normal senses. Although the mucosa of left lateral nasal wall remained normal, it was oppressed medially by the mass and the nasal cavity was nearly occluded. The left hard palate and the outer gum from the second incisor in the upper left jaw were swollen; the area was elastic hard on palpation and a bone defect was suspected. The mass was tender but not painful. Pulsation was not detected in the mass. None of impairment of ocular movement, double vision, limitation of mouth opening or nose bleeding was observed. Blood and urinary tests; nothing abnormal. Radiographic findings; radiograph showed a groundglass-like appearance in the left maxillary sinus (Fig. 1), and tomography showed a defect of medial, lateral and inferior wall of the maxillary sinus (Fig. 2). CT findings; CT showed an expansile soft tissue mass in the left maxillary sinus. The mass was surrounded by
0385-8146/01/$ - see front matter © 2001 Elsevier Science Ireland Ltd. All rights reserved. PII: S 0 3 8 5 - 8 1 4 6 ( 0 1 ) 0 0 0 8 4 - 0
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F. Suzuki et al. / Auris Nasus Larynx 28 (2001) S131–S137
Fig. 1. Radiographic finding by Walters’ method. Ground-glass-like appearance is observed in the left maxillary sinus.
Fig. 2. Tomography of the mass, showing a defect of medial, lateral and inferior wall of the maxillary sinus.
thin bony wall. The inside was enhanced heterogeneously (Fig. 3a). A wedge-shaped bony shadow was observed under the orbital floor in the coronal section (Fig. 3b). No apparent invasion of the surrounding tissue was observed. Magnetic resonance imaging (MRI) findings; the margin of the mass was well defined. The inside showed homogeneous and intermediate signal intensity on T1weighted image (Fig. 4a), which was enhanced to be net-like signal on gadolinium (Gd)-enhanced image (Fig. 4b). On T2-weighted image, multiple internal septations were revealed; formation of fluid-fluid levels was observed in a part, and signal intensity was high above
the fluid level and intermediate under the fluid level (Fig. 4c). The wedge-shaped bony shadow on CT was low on T2-weighted image, and relatively high on Gdenhanced image; the signals differed from those of other osteo-wall (Fig. 4d and e). From these findings, the lesion was suspected to be a sponge-like mass containing fluid such as blood. For definite diagnosis, biopsy was carried out under local anesthesia by trans-canine fossa approach. Biopsy findings indicated that the mass was covered with periosteum or mass capsule. When we opened it, nothing solid was found inside; instead, connective tissue was sparsely found and blood was filling the spaces within
Fig. 3. (a) Axial CT scan view of the mass. The mass is expanding the maxillary sinus. (b) Coronal CT scan view of the mass. A wedge-shaped bony shadow is observed under the orbital floor.
F. Suzuki et al. / Auris Nasus Larynx 28 (2001) S131–S137 S133
Fig. 4. (a) An axial T1-weighted MR image, showing homogeneous to intermediate signal intensity inside the mass. (b) An axial Gd-enhanced MR image, showing net-like signal within the mass lesion. (c) An axial T2-weighted MR image, showing multiple internal septations and formation of fluid-fluid levels (Arrow). (d) Coronal T2-weighted MR image, showing a wedge-shaped area of low signal intensity. (e) Coronal Gd-enhanced MR image. The wedge-shaped area is enhanced.
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the tissue. A specimen was taken and subjected to histopathological diagnosis. Bleeding was in a small degree and hemostasis was obtained by compression. Pathological diagnosis was a non-malignant mass with suspicion of cavernous hemangioma. Angiographic findings; as hemangioma was suspected from the biopsy result, we performed angiography to determine the nutrient artery and to embolize it. Although the mass margin was clearly marked on the angiography of the left external carotid artery (Fig. 5), it was not diagnostic of either hemangioma or malignant tumor. The nutrient artery was not identified and thus embolization was not performed. Surgical findings; on December 12, 1996, partial resection of the maxillary sinus was performed by transcanine fossa approach. The mass was covered with hard capsule of connective tissue, and the capsule was partially very thin and partially as hard as bone. It slightly adhered to the adjacent tissue, but detaching along the capsulated surface was relatively easy. The anterior, exterior, posterior and interior wall of the maxilla was nearly entirely lost and the center of the inferior wall was also lost. The hard palate retained only fibrous mucosal tissue, but it was solid enough and reinforcement was not done. The mass was generally soft, containing blood, which leaked out while we proceeded resection, reducing the size of the mass to half. Thereby we secured a good view of the area, and removed the mass including the lateral nasal wall without making an incision in the face. There was no vascular bleeding during operation, and the total amount of blood loss was 500 ml, mainly by oozing. Pathological findings; hematoxylin and eosin staining revealed a sponge-like portion, containing fibrous septa composed of multi-nucleated giant cells and bone tissue, and lumens of blood vessels devoid of endothelial cells, and a solid portion, containing mesenchymal cells forming small immature bone or osteoid tissue (Fig. 6). The former was a feature of ABC and the latter was that of fibrous dysplasia; hence it was diagnosed as secondary ABC associated with fibrous dysplasia. There was no impairment of mouth opening or food intake after operation, and the patient was discharged from hospital in January, 1997. After discharge, he was followed up by his previous doctor, and in late June, 1998, a swelling developed in the floor of nasal cavity, which appeared to be a recurrence, and gradually grew larger to occlude the nasal cavity. He was re-admitted to our hospital for expected operation. MRI findings at recurrence; recurrent lesion was detected in the area from the left maxillary sinus to the left nasal cavity. It was intermediate on T1weighted image, high on T2-weighted image, and net-like on Gd-enhanced image. There was no finding of conspicuous formation of fluid-fluid levels (Fig. 7a– d).
On April 8, 1999, trans-canine fossa approach was done as in the previous operation and the mass was resected. The mass had septa composed of osteo-tissue, which had degenerated into sponge-like matter, forming multiple cysts, which contained serum instead of blood. The mass, which had been filling the maxilla was enucleated, and the operation was completed. Pathological diagnosis of the lesion was fibrous dysplasia. Presently one and a half years after the operation, there has been no sign of recurrence.
3. Discussion Aneurysmal bone cyst is non-neoplastic, expansile bone lesion, consisting of sponge-like cavities of various sizes, which contain either blood or serum. It was firstly reported by Jaffe and Lichtenstein in 1942 [1], and was named ABC in 1950 [2]. This terminology was not derived from its histopathological findings, but from its similarity to aneurysm on its radiographic images; it appears like aneurysm because contour of the affected bone expands; however, it has no pulsation and thus it is not real aneurysm. Whereas it has a multi-cystic structure, the cavities are not lined with endothelium and are therefore not true cysts. Macroscopically it is often described as ‘blood-filled sponge’. Histologically, ABC is composed of spaces separated by septa. The spaces contain either serum or blood. The septum is composed of fibroblasts, myofibroblasts, multinucleated giant cells like osteoclasts, osteoid, and woven bone. The lining cells of the septum are not endothelial [3,4]. Depending on the presence or absence of the pre-existing lesion, ABC lesions are classified into ‘primary’
Fig. 5. Angiography of the left external carotid artery. The periphery of the mass is densely stained (arrow).
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Fig. 6. Histology of the mass. It contains fibrous septa composed of multinucleated giant cells and bone tissue, and lumens of blood vessels devoid of endothelial cells.
and ‘secondary’. In approximately one third of cases, the pre-existing lesion can be clearly identified. The most common of these is giant cell tumor; other common lesions are osteoblastoma, angioma and chondroblastoma [3]. Fibrous dysplasia, as in the present case, is a less common pre-existing lesion in general; however, there are a number of descriptions of fibrous dysplasia as pre-existing lesion as far as the reports of ABC developed in the head and neck region are concerned [5–8]. Probably this is related with the fact that incidences of fibrous dysplasia in the head and neck region are relatively high. According to a recent report, ABC is basically a secondary lesion, and in the cases diagnosed as primary lesion, it is speculated that the pre-existing lesion may have been overlooked or the morphological changes to ABC may have erased the trace of the pre-existing lesion [3]. The etiology of ABC is unknown. It is speculated that some pre-existing lesion caused venous occlusion or arterioveous malformation and creates a secondary reactive lesion of bone via hemodynamic forces [3]. The average age at diagnosis ranges between 16 and 18, and about 80% are in the range of 5– 20 [3]. No marked difference is observed between the sexes; however, incidences are slightly higher in female than in male. The most frequent lesion site is metaphysis of the long bones, followed by femur, shank, fibula and humerus, which account for approximately 45% of all [4], and further followed by vertebra and pelvis; only 2% are in the head and neck region [9]. In a report of 77 cases of ABC developed in the head and neck region, 31 were in the mandible, 20 in the maxilla, one in the zygoma, and the rest were mainly in the skull including ethmoid bone and temporal bone; nearly two thirds were in the maxilla and mandible [9].
The most common clinical symptoms are local pain and swelling which continue for several months, and throbbing pain, tenderness and decreased range of motion are also common. Diagnosis is made mostly from image findings for its characteristic morphology. Radiographs typically show an eccentric, lytic lesion with an expanded, remodeled ‘blown-out’ or ‘ballooned’ bony contour of the host bone. Lesions frequently show a delicate trabeculated appearance [3]. However, in the cases of maxillary sinus lesion as in the present case, often ground-glass-like appearance is shown; it is difficult to differentiate it from other neoplastic lesions only on radiographic findings. CT shows the characteristics of the lesion better. The lesion is shown as an image of an expansile soft tissue mass, and is often well defined from the surrounding tissue by thin rim of dense bone like eggshell. This is because of periosteal new bone formation, suggesting a slowly growing, benign lesion. Sometimes internal septations and fluid-fluid levels are present. There is a report that internal septa were enhanced by contrast medium. In the present case, the lesion inside was enhanced heterogeneously on CT, which probably indicated the septa. MRI is more diagnostic as it shows the intrastructure even clearly. The lesion is surrounded by a thin, welldefined, low-signal rim, and the inside is loculated by low-signal septa. These low-signal septa are thought to be due to fibrous tissue. The signal of one loculation differs from that of the adjacent loculation, and some of the loculations have formation of fluid-fluid levels. On T2-weighted image, fluid-fluid levels cause the loculations to be divided into an upper hyperintense portion and a lower iso- or hypointense part [4,6,10]. These fluid levels are thought to represent sedimentation of
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red blood cells, separating from serum. To demonstrate the fluid levels more clearly, the patient must remain motionless for at least 10 min before scanning [11]. In the present case, on T1-weighted image, the cyst presented intermediate signal intensity, but on Gd-enhanced image, the septa presented high signal intensity, showing a net-like image; and on T2-weighted image, the structure of the numerous cysts was shown, which had individually different signal intensities, and some of them had formation of fluid-fluid levels. These were the most characteristic findings of ABC. Although it is relatively easy to diagnose ABC from image findings, particularly those of MRI, it is important to determine presence or absence of the pre-existing lesion histopathologically for definite diagnosis. When the pre-existing lesion cannot be identified, the lesion is diagnosed as primary ABC. Then, it is important to differentiate it from giant cell tumor or telangiectatic osteosarcoma. Compared with the former, the
background cells in ABC are more fibrogenic and it occurs in the metaphysis of long bones in young people, and compared with the latter, there is no cytologic atypia in ABC [12]. In the head and neck region, there are a number of descriptions of fibrous dysplasia as pre-existing lesion as far as the reports of ABC developed are concerned [5–8]. Therefore, if ABC has been detected in the head and neck region, fibrous dysplasia should be suspected. In the present case, too, there was a pathological finding of fibrous dysplasia besides that of ABC, and thus it was diagnosed as ABC associated with fibrous dysplasia. Retrospectively we recognize a wedge-shaped bony shadow under the orbital floor on CT, which we assume represented the portion of fibrous dysplasia. If the pre-existing lesion has been identified, it is necessary to treat it. If it is not known, surgery is the first choice. As ABCs are benign, simple curettage is usually performed to preserve function or cosmetic
Fig. 7. MR images at recurrence; (a) Axial T1-weighted. (b) Axial Gd-enhanced. (c) Coronal T2-weighted. (d) Coronal Gd-enhanced.
F. Suzuki et al. / Auris Nasus Larynx 28 (2001) S131–S137
appearance. Probably for this reason, recurrence is seen approximately in 20% of the cases [4]. There is a report that recurrence rate was reduced by combining curettage with cryosurgery [13]. Another report demonstrates that selective arterial embolization applied to inoperative site achieved favorable results [14]. For preservation of the function and cosmetic appearance, enucleation is frequently selected in the cases of head and neck region. Since 90% of postoperative recurrences occur within 2 years after operation, close observation with serial radiographic examinations for at least 2 years should be sufficient in most cases [4]. In the present case, we performed angiography as cavernous hemangioma was suspected from biopsy findings. However, no characteristic finding of hemangioma was observed, and enucleation of the mass was carried out with suspicion of some benign lesion. Although it turned out that the pre-existing lesion was fibrous dysplasia and that the treatment was appropriate, there was a recurrence at a year and a half after the operation, which required second surgery. In general, fibrous dysplasia ceases to grow with aging and hardly grows malignant, and thus it is generally thought appropriate to perform local resection of the swelling if the lesion is in the facial bone. The second operation in our case, too, was enucleation. Currently a year and a half after the operation, there has been no sign of another recurrence. Further careful follow-up is yet necessary.
4. Conclusion We reported a case of ABC associated with fibrous dysplasia in the maxillary sinus. The characteristic feature of the lesion, i.e. a structure of multiple cysts containing fluid-fluid levels was clearly revealed on MRI. We suggest that MRI is very useful for the diagnosis of ABC. ABC is thought to follow other lesions, and thus when treating ABC, it is important to determine
.
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whether any pre-existing lesion has preceded or not; in particular, if the lesion site is in the head and neck region, we should note that fibrous dysplasia may have been pre-existing lesion. References [1] Jaffe HL, Lichtenstein L. Solitary unicameral bone cyst with emphasis on the roentgen picture, the pathologic appearance, and the pathogenesis. Arch Surg 1942;44:1004 – 25. [2] Lichtensten L. Aneurysmal bone cyst. A pathological entity commonly mistaken for giant cell tumor and occasionally for hemangioma and osteogenic sarcoma. Cancer 1950;3:279 –89. [3] Kransdorf MJ, Sweet DE. Aneurysmal bone cyst: concept, controversy, clinical presentation, and imaging. Am J Roentgenol 1995;164:573 – 80. [4] Ariel M, De Dios V, Bond JR, Shives TC, McLeod RA, Unni KK. Aneurysmal bone cyst: a clinicopathologic study of 238 cases. Cancer 1992;69:2921 – 31. [5] Arden RL, Bahu SJ, Lucas DR. Mandibular aneurysmal bone cyst associated with fibrous dysplasia. Otolaryngol Head Neck Surg 1997;117:s153 – 6. [6] Som PM, Schatz CJ, Flaum EG, Lanman TH. Aneurysmal bone cyst of the paranasal sinuses associated with fibrous dysplasia: CT and MR findings. J Comput Assist Tomogr 1991;15:513 –5. [7] Citardi MJ, Janjua T, Abrahams JJ, Sasaki CT. Orbitoethmoid aneurysmal bone cyst. Otolaryngol Head Neck Surg 1996;114:466 – 70. [8] Park AH, Phillips J, Forte V. Aneurysmal bone cyst of the temporal bone. Otolaryngol Head Neck Surg 1999;120:606 –10. [9] Matt BH. Aneurysmal bone cyst of the maxilla; case report and review of the literature. Int J Pediatr Otorhinolaryngol 1993;25:217 – 26. [10] Munk PL, Helms CA, Holt RG, Johnson J, Steinbach L, Neumann C. MR imaging of aneurysmal bone cysts. Am J Roentgenol 1989;153:99 – 101. [11] Beltran J, Simon DC, Levy M, Herman L, Weis L, Mueller CF. Aneurysmal bone cysts: MR imaging at 1.5T1. Radiology 1986;158:689 – 90. [12] Sternberg S.S., Diagnostic Surgical Pathology, 2nd Edn. 1994; 307 – 309. [13] Marcove RC, Sheth DS, Takemoto S, Healey JH. The treatment of aneurysmal bone cyst. Clin Orthop Relat Res 1995;311:157 – 63. [14] De Cristofaro R, Biagini R, Boriani S, Ricci S, Ruggieri P, Rossi G, Fabbri N, Roversi R. Selective arterial embolization in the treatment of aneurysmal bone cyst and angioma of bone. Skelet Radiol 1992;21:523 – 7.
A rare aneurysmal bone cyst of the maxillary sinus: a case report Fumiyuki Suzuki *, Satoshi Fukuda, Katsunori Yagi, Eiji Chida, Yukio Inuyama Department of Otolaryngology, Hokkaido Uni6ersity School of Medicine, kita 15 nishi 7, kita-ku, Sapporo, 060 -8638 Japan Received 5 January 2001; received in revised form 6 February 2001; accepted 8 February 2001
Abstract Aneurysmal bone cyst (ABC) is a non-neoplastic expansile bone lesion that is common in the long bones; only 2% occurs in the head and neck. We present a case of ABC in a 23-year-old male and describe the clinical and radiological features, histopathology and treatment. Magnetic resonance imaging (MRI) demonstrated multiple internal septations, cysts with fluid-fluid levels of varying intensity, and an intact rim of low-intensity signal completely surrounding the lesion. The tumor was removed by enucleation with resection of the lateral nasal cavity. Histopathologic diagnosis was ABC and fibrous dysplasia. We suggest that MRI is very useful for the diagnosis of ABC. ABC is thought to follow other lesions, and thus when treating ABC, it is important to determine whether any pre-existing lesion has preceded or not; in particular, if the lesion site is in the head and neck region. © 2001 Elsevier Science Ireland Ltd. All rights reserved. Keywords: Aneurysmal bone cyst; MRI; CT
1. Introduction Aneurysmal bone cyst (ABC) is a non-neoplastic bone lesion developing mainly in the long bones, which rarely occurs in the head and neck region. We have experienced a case of aneurysmal bone cyst developed in the maxillary sinus. We present the case and discuss the characteristics on imaging with some references to pertinent literature.
2. A case report Patient: a 23-year-old man. Chief complaint: swelling of the left cheek. Family history: nothing particular. Previous history: neither trauma in the face nor operation of paranasal sinus. There was nothing particular. Present history: since June 1996, he noticed swelling of the left cheek. As he had no pain, he left it. However, as the swelling gradually enlarged, he consulted a * Corresponding author. Tel.: + 81-11-7073387; fax: +81-117177566. E-mail address: [email protected] (F. Suzuki).
otolaryngologist nearby. Fine needle aspiration cytology was performed from the lesion and the cells of the lesion consisted of hematocyte only. Then, he was referred to our Department of Otolaryngology, Hokkaido University Hospital for further examination. Findings at the first visit; the left cheek was conspicuously swollen. The lesion was elastic hard on palpation. The skin surface of left cheek had no abnormality and maintained normal senses. Although the mucosa of left lateral nasal wall remained normal, it was oppressed medially by the mass and the nasal cavity was nearly occluded. The left hard palate and the outer gum from the second incisor in the upper left jaw were swollen; the area was elastic hard on palpation and a bone defect was suspected. The mass was tender but not painful. Pulsation was not detected in the mass. None of impairment of ocular movement, double vision, limitation of mouth opening or nose bleeding was observed. Blood and urinary tests; nothing abnormal. Radiographic findings; radiograph showed a groundglass-like appearance in the left maxillary sinus (Fig. 1), and tomography showed a defect of medial, lateral and inferior wall of the maxillary sinus (Fig. 2). CT findings; CT showed an expansile soft tissue mass in the left maxillary sinus. The mass was surrounded by
0385-8146/01/$ - see front matter © 2001 Elsevier Science Ireland Ltd. All rights reserved. PII: S 0 3 8 5 - 8 1 4 6 ( 0 1 ) 0 0 0 8 4 - 0
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Fig. 1. Radiographic finding by Walters’ method. Ground-glass-like appearance is observed in the left maxillary sinus.
Fig. 2. Tomography of the mass, showing a defect of medial, lateral and inferior wall of the maxillary sinus.
thin bony wall. The inside was enhanced heterogeneously (Fig. 3a). A wedge-shaped bony shadow was observed under the orbital floor in the coronal section (Fig. 3b). No apparent invasion of the surrounding tissue was observed. Magnetic resonance imaging (MRI) findings; the margin of the mass was well defined. The inside showed homogeneous and intermediate signal intensity on T1weighted image (Fig. 4a), which was enhanced to be net-like signal on gadolinium (Gd)-enhanced image (Fig. 4b). On T2-weighted image, multiple internal septations were revealed; formation of fluid-fluid levels was observed in a part, and signal intensity was high above
the fluid level and intermediate under the fluid level (Fig. 4c). The wedge-shaped bony shadow on CT was low on T2-weighted image, and relatively high on Gdenhanced image; the signals differed from those of other osteo-wall (Fig. 4d and e). From these findings, the lesion was suspected to be a sponge-like mass containing fluid such as blood. For definite diagnosis, biopsy was carried out under local anesthesia by trans-canine fossa approach. Biopsy findings indicated that the mass was covered with periosteum or mass capsule. When we opened it, nothing solid was found inside; instead, connective tissue was sparsely found and blood was filling the spaces within
Fig. 3. (a) Axial CT scan view of the mass. The mass is expanding the maxillary sinus. (b) Coronal CT scan view of the mass. A wedge-shaped bony shadow is observed under the orbital floor.
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Fig. 4. (a) An axial T1-weighted MR image, showing homogeneous to intermediate signal intensity inside the mass. (b) An axial Gd-enhanced MR image, showing net-like signal within the mass lesion. (c) An axial T2-weighted MR image, showing multiple internal septations and formation of fluid-fluid levels (Arrow). (d) Coronal T2-weighted MR image, showing a wedge-shaped area of low signal intensity. (e) Coronal Gd-enhanced MR image. The wedge-shaped area is enhanced.
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the tissue. A specimen was taken and subjected to histopathological diagnosis. Bleeding was in a small degree and hemostasis was obtained by compression. Pathological diagnosis was a non-malignant mass with suspicion of cavernous hemangioma. Angiographic findings; as hemangioma was suspected from the biopsy result, we performed angiography to determine the nutrient artery and to embolize it. Although the mass margin was clearly marked on the angiography of the left external carotid artery (Fig. 5), it was not diagnostic of either hemangioma or malignant tumor. The nutrient artery was not identified and thus embolization was not performed. Surgical findings; on December 12, 1996, partial resection of the maxillary sinus was performed by transcanine fossa approach. The mass was covered with hard capsule of connective tissue, and the capsule was partially very thin and partially as hard as bone. It slightly adhered to the adjacent tissue, but detaching along the capsulated surface was relatively easy. The anterior, exterior, posterior and interior wall of the maxilla was nearly entirely lost and the center of the inferior wall was also lost. The hard palate retained only fibrous mucosal tissue, but it was solid enough and reinforcement was not done. The mass was generally soft, containing blood, which leaked out while we proceeded resection, reducing the size of the mass to half. Thereby we secured a good view of the area, and removed the mass including the lateral nasal wall without making an incision in the face. There was no vascular bleeding during operation, and the total amount of blood loss was 500 ml, mainly by oozing. Pathological findings; hematoxylin and eosin staining revealed a sponge-like portion, containing fibrous septa composed of multi-nucleated giant cells and bone tissue, and lumens of blood vessels devoid of endothelial cells, and a solid portion, containing mesenchymal cells forming small immature bone or osteoid tissue (Fig. 6). The former was a feature of ABC and the latter was that of fibrous dysplasia; hence it was diagnosed as secondary ABC associated with fibrous dysplasia. There was no impairment of mouth opening or food intake after operation, and the patient was discharged from hospital in January, 1997. After discharge, he was followed up by his previous doctor, and in late June, 1998, a swelling developed in the floor of nasal cavity, which appeared to be a recurrence, and gradually grew larger to occlude the nasal cavity. He was re-admitted to our hospital for expected operation. MRI findings at recurrence; recurrent lesion was detected in the area from the left maxillary sinus to the left nasal cavity. It was intermediate on T1weighted image, high on T2-weighted image, and net-like on Gd-enhanced image. There was no finding of conspicuous formation of fluid-fluid levels (Fig. 7a– d).
On April 8, 1999, trans-canine fossa approach was done as in the previous operation and the mass was resected. The mass had septa composed of osteo-tissue, which had degenerated into sponge-like matter, forming multiple cysts, which contained serum instead of blood. The mass, which had been filling the maxilla was enucleated, and the operation was completed. Pathological diagnosis of the lesion was fibrous dysplasia. Presently one and a half years after the operation, there has been no sign of recurrence.
3. Discussion Aneurysmal bone cyst is non-neoplastic, expansile bone lesion, consisting of sponge-like cavities of various sizes, which contain either blood or serum. It was firstly reported by Jaffe and Lichtenstein in 1942 [1], and was named ABC in 1950 [2]. This terminology was not derived from its histopathological findings, but from its similarity to aneurysm on its radiographic images; it appears like aneurysm because contour of the affected bone expands; however, it has no pulsation and thus it is not real aneurysm. Whereas it has a multi-cystic structure, the cavities are not lined with endothelium and are therefore not true cysts. Macroscopically it is often described as ‘blood-filled sponge’. Histologically, ABC is composed of spaces separated by septa. The spaces contain either serum or blood. The septum is composed of fibroblasts, myofibroblasts, multinucleated giant cells like osteoclasts, osteoid, and woven bone. The lining cells of the septum are not endothelial [3,4]. Depending on the presence or absence of the pre-existing lesion, ABC lesions are classified into ‘primary’
Fig. 5. Angiography of the left external carotid artery. The periphery of the mass is densely stained (arrow).
F. Suzuki et al. / Auris Nasus Larynx 28 (2001) S131–S137
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Fig. 6. Histology of the mass. It contains fibrous septa composed of multinucleated giant cells and bone tissue, and lumens of blood vessels devoid of endothelial cells.
and ‘secondary’. In approximately one third of cases, the pre-existing lesion can be clearly identified. The most common of these is giant cell tumor; other common lesions are osteoblastoma, angioma and chondroblastoma [3]. Fibrous dysplasia, as in the present case, is a less common pre-existing lesion in general; however, there are a number of descriptions of fibrous dysplasia as pre-existing lesion as far as the reports of ABC developed in the head and neck region are concerned [5–8]. Probably this is related with the fact that incidences of fibrous dysplasia in the head and neck region are relatively high. According to a recent report, ABC is basically a secondary lesion, and in the cases diagnosed as primary lesion, it is speculated that the pre-existing lesion may have been overlooked or the morphological changes to ABC may have erased the trace of the pre-existing lesion [3]. The etiology of ABC is unknown. It is speculated that some pre-existing lesion caused venous occlusion or arterioveous malformation and creates a secondary reactive lesion of bone via hemodynamic forces [3]. The average age at diagnosis ranges between 16 and 18, and about 80% are in the range of 5– 20 [3]. No marked difference is observed between the sexes; however, incidences are slightly higher in female than in male. The most frequent lesion site is metaphysis of the long bones, followed by femur, shank, fibula and humerus, which account for approximately 45% of all [4], and further followed by vertebra and pelvis; only 2% are in the head and neck region [9]. In a report of 77 cases of ABC developed in the head and neck region, 31 were in the mandible, 20 in the maxilla, one in the zygoma, and the rest were mainly in the skull including ethmoid bone and temporal bone; nearly two thirds were in the maxilla and mandible [9].
The most common clinical symptoms are local pain and swelling which continue for several months, and throbbing pain, tenderness and decreased range of motion are also common. Diagnosis is made mostly from image findings for its characteristic morphology. Radiographs typically show an eccentric, lytic lesion with an expanded, remodeled ‘blown-out’ or ‘ballooned’ bony contour of the host bone. Lesions frequently show a delicate trabeculated appearance [3]. However, in the cases of maxillary sinus lesion as in the present case, often ground-glass-like appearance is shown; it is difficult to differentiate it from other neoplastic lesions only on radiographic findings. CT shows the characteristics of the lesion better. The lesion is shown as an image of an expansile soft tissue mass, and is often well defined from the surrounding tissue by thin rim of dense bone like eggshell. This is because of periosteal new bone formation, suggesting a slowly growing, benign lesion. Sometimes internal septations and fluid-fluid levels are present. There is a report that internal septa were enhanced by contrast medium. In the present case, the lesion inside was enhanced heterogeneously on CT, which probably indicated the septa. MRI is more diagnostic as it shows the intrastructure even clearly. The lesion is surrounded by a thin, welldefined, low-signal rim, and the inside is loculated by low-signal septa. These low-signal septa are thought to be due to fibrous tissue. The signal of one loculation differs from that of the adjacent loculation, and some of the loculations have formation of fluid-fluid levels. On T2-weighted image, fluid-fluid levels cause the loculations to be divided into an upper hyperintense portion and a lower iso- or hypointense part [4,6,10]. These fluid levels are thought to represent sedimentation of
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red blood cells, separating from serum. To demonstrate the fluid levels more clearly, the patient must remain motionless for at least 10 min before scanning [11]. In the present case, on T1-weighted image, the cyst presented intermediate signal intensity, but on Gd-enhanced image, the septa presented high signal intensity, showing a net-like image; and on T2-weighted image, the structure of the numerous cysts was shown, which had individually different signal intensities, and some of them had formation of fluid-fluid levels. These were the most characteristic findings of ABC. Although it is relatively easy to diagnose ABC from image findings, particularly those of MRI, it is important to determine presence or absence of the pre-existing lesion histopathologically for definite diagnosis. When the pre-existing lesion cannot be identified, the lesion is diagnosed as primary ABC. Then, it is important to differentiate it from giant cell tumor or telangiectatic osteosarcoma. Compared with the former, the
background cells in ABC are more fibrogenic and it occurs in the metaphysis of long bones in young people, and compared with the latter, there is no cytologic atypia in ABC [12]. In the head and neck region, there are a number of descriptions of fibrous dysplasia as pre-existing lesion as far as the reports of ABC developed are concerned [5–8]. Therefore, if ABC has been detected in the head and neck region, fibrous dysplasia should be suspected. In the present case, too, there was a pathological finding of fibrous dysplasia besides that of ABC, and thus it was diagnosed as ABC associated with fibrous dysplasia. Retrospectively we recognize a wedge-shaped bony shadow under the orbital floor on CT, which we assume represented the portion of fibrous dysplasia. If the pre-existing lesion has been identified, it is necessary to treat it. If it is not known, surgery is the first choice. As ABCs are benign, simple curettage is usually performed to preserve function or cosmetic
Fig. 7. MR images at recurrence; (a) Axial T1-weighted. (b) Axial Gd-enhanced. (c) Coronal T2-weighted. (d) Coronal Gd-enhanced.
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appearance. Probably for this reason, recurrence is seen approximately in 20% of the cases [4]. There is a report that recurrence rate was reduced by combining curettage with cryosurgery [13]. Another report demonstrates that selective arterial embolization applied to inoperative site achieved favorable results [14]. For preservation of the function and cosmetic appearance, enucleation is frequently selected in the cases of head and neck region. Since 90% of postoperative recurrences occur within 2 years after operation, close observation with serial radiographic examinations for at least 2 years should be sufficient in most cases [4]. In the present case, we performed angiography as cavernous hemangioma was suspected from biopsy findings. However, no characteristic finding of hemangioma was observed, and enucleation of the mass was carried out with suspicion of some benign lesion. Although it turned out that the pre-existing lesion was fibrous dysplasia and that the treatment was appropriate, there was a recurrence at a year and a half after the operation, which required second surgery. In general, fibrous dysplasia ceases to grow with aging and hardly grows malignant, and thus it is generally thought appropriate to perform local resection of the swelling if the lesion is in the facial bone. The second operation in our case, too, was enucleation. Currently a year and a half after the operation, there has been no sign of another recurrence. Further careful follow-up is yet necessary.
4. Conclusion We reported a case of ABC associated with fibrous dysplasia in the maxillary sinus. The characteristic feature of the lesion, i.e. a structure of multiple cysts containing fluid-fluid levels was clearly revealed on MRI. We suggest that MRI is very useful for the diagnosis of ABC. ABC is thought to follow other lesions, and thus when treating ABC, it is important to determine
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