- Email: [email protected]
Calcifying aponeurotic fibroma with bone islands exhibiting hematopoiesis: a case report and review of the literature
Calcifying aponeurotic fibroma with bone islands exhibiting hematopoiesis: a case report and review of the literature Jill M. Kramer, DDS, PhDa, Jesse C. Doscher, DDS, MSca, Mikhail Ruvinsky, DDS, MDb, and John E. Fantasia, DDS,c New Hyde Park, New York DEPARTMENT OF DENTAL MEDICINE, LONG ISLAND JEWISH MEDICAL CENTER
Aponeurotic fibroma (AF) was originally described by Keasbey in 1953 as juvenile aponeurotic fibroma, most commonly occurring in the distal extremities. Initially described in children and adolescents, AF is now recognized to occur over a wide age range and at various anatomic sites. A variant of this lesion, termed calcifying aponeurotic fibroma (CAF) has been described. CAF is a slow-growing, solitary, and painless nodule often adherent to tendon, fascia, or periosteum. We report a patient who presented with a firm lobulated mass, portions of which were fixed to the left ascending mandibular ramus. The lesion represented a CAF arising juxtacortical to the mandible, with the calcified component composed of mature bone exhibiting focal areas of hematopoiesis. Additional reports of CAF occurring in the head and neck region are reviewed. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2010;109:878-882)
Calcifying aponeurotic fibroma (CAF) was originally described by Keasbey in 1953 as a lesion in children which arises on the palms and soles,1 and has subsequently been described in other anatomic sites and occurring over a wide age range.2 Although CAF occurs primarily in the limbs, cases arising in the head and neck region are documented (Table I). The present report discusses a paracortical lesion of this type in the maxillofacial region and reviews the current literature on this rare entity. CASE REPORT A 62-year-old woman presented for evaluation of a progressively enlarging mass overlying the left ascending ramus and extending medially and laterally. The mass was visible on oral examination beneath the mucosa and was firm to palpation (Fig. 1). There was a history of biopsy of a small submucosal nodule in this same area 12 years earlier. The histopathology at that time was a descriptive diagnosis of oral mucosa with underlying loose fibrous connective tissue admixed with a few dilated endothelial lined channels; neoplasia was not identified in that biopsy. The clinical history and subsequent identification of the current mass suggested that representative tissue was not obtained. The lesion continued to enlarge slowly over the next 12 years, aaccording to patient history. There was no interval follow-up evaluation before establishing the diagnosis of CAF with biopsy. The patient’s
a
Resident, Oral and Maxillofacial Pathology. Resident, Oral and Maxillofacial Surgery. c Chief, Oral and Maxillofacial Pathology. The first two authors contributed equally to this work. Received for publication Jan 16, 2010; accepted for publication Jan 26, 2010. 1079-2104/$ - see front matter © 2010 Mosby, Inc. All rights reserved. doi:10.1016/j.tripleo.2010.01.020 b
878
medical history was significant for heart murmur, hypertension, hypercholesterolemia, and diabetes mellitus. She had a 40 pack-year history of cigarette smoking. The patient reported no known drug allergies, and her medications included quinaretic (Quinapril), nateglinide (Starlix), metoprolol (Toprol), metformin (Glucophage), simvastatin (Zocor), and aspirin. Clinically, the lesion presented as a submucosal swelling in the area of the left ascending ramus. The overlying mucosa was normal in color and not ulcerated. The clinical differential diagnoses included a wide variety of pathologic processes, including those of mesenchymal, neurogenic, and vascular origin. In addition, odontogenic and nonodontogenic processes, as well as a tumor of minor salivary gland or parotid gland were included in the differential diagnosis. A lymphoproliferative process was also considered, because of the location and size of the lesion. Imaging studies of the lesion demonstrated a soft tissue mass with calcifications without lytic changes to underlying bone (Fig. 2). Computerized tomographic scan of the lesion revealed an expansile mass of the left posterior mandible and ascending ramus with smooth cupping of medial ramus cortical bone. The lesion was well defined and lobulated and contained foci of ovoid to crescent-shaped bone. The mass extended to the intercondylar notch with lateral extension and possible displacement and compression of the left parotid duct. There was no infiltration into surrounding soft tissues, and no periosteal reaction was seen. Notably, the lesion was of sufficient size to compress the left posterior lateral tongue (Fig. 2, B). Upon imaging, the clinical differential was narrowed considerably, with the lesion appearing as a soft tissue mass with a mineralized component in a paracortical region of the left mandibular ramus. The radiographic differential diagnosis included lesions that may arise peripherally and cause bony erosion. Lesions with these characteristics in the maxillofacial region may include a peripheral calcifying epithelial odontogenic tumor, calcifying ghost cell odontogenic
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Table I. Cases of calcifying aponeurotic fibroma arising in the head and neck Case
Age (yrs)/ gender
Location
Size (cm)
Reference
1 2 3 4 5
6/M 60/F 3/M 5/F 62/F
Base of neck Medial pterygoid muscle Scalp Neck Juxtacortical to mandible
1 1 4 10 4.8
2 3 9 10 Present report
cytologic atypia were not observed. In some areas, a fibrocartilage-like pattern was seen, along with distinct bony islands. The histopathologic features were interpreted to be representative of CAF. This diagnosis was established with a generous biopsy and confirmed upon examination of the surgical excision. It is likely that this tumor represents the smaller mass described 12 years prior without the sampling of representative tissue. CAF grows slowly and rarely achieves the size documented here (Table I). Surgical excision is the recommended treatment for CAF. The current lesion was dissected from the surrounding tissues without difficulty; the adjacent mandibular bone was mechanically curetted. Local recurrences have been reported in 50% of patients for lesions reported at other anatomic sites.2 The patient continues to be followed-up at 3-month intervals and remained free of disease 1 year after surgery.
LITERATURE REVIEW
Fig. 1. Clinical presentation. The patient presented with a large submucosal nodule in her left ascending ramus. The nodule was firm to palpation, and the overlying mucosa was nonulcerated and normal in color.
cyst and tumor variants, giant cell granuloma, and salivary tumor with calcifications. To resect the lesion surgically, the patient was placed under general anesthesia and an incision made through the mucosa and submucosa along the left external oblique ridge of the mandible. At this time, the capsule of the lesion was clearly identified and appeared to be separate from the surrounding soft tissue except for a tendinous tract that appeared to be originating from the medial pterygoid muscle. Using a combination of blunt and sharp dissection, the lesion was carefully separated from the surrounding soft tissue and removed in its entirety as a single specimen. Upon examination, the lesion appeared as a large lobulated mass of tan soft tissue. A tendon was noted in continuity with the medial pole of the mass (Fig. 3). Upon sectioning, a firm gritty consistency was evident. Histologically, the lesion was composed of bland hypocellular to moderately cellular fibrous tissue with areas suggestive of a fibromatosis-like pattern as well as multiple circular foci of mature bone (Fig. 4). Some of the bone islands contained hematopoietic marrow. The fibrous tissue component demonstrated varying amounts of cellularity, with intervening dense collagenous stroma. Fibroblasts with round to ovoid nuclei were present (Fig. 4, C and D), and mitoses and
Clinical presentation Calcifying aponeurotic fibroma has classically been described as a nontender soft tissue neoplasm with a predilection for the proximal extremities. The lesion is most commonly found on the palms of the hands, soles of the feet and fingers, and less frequently occurs on ankles and wrists.1,2 A case of CAF arising in the medial pterygoid muscle has been reported;3 that patient presented with mild tenderness, and computerized tomography revealed a 1-cm calcifying mass.3 The lesion was dissected away from the muscle, and gross examination demonstrated the medial pterygoid tendon within the specimen.3 Although few cases of CAF are documented, it seems to have a male predominance, particularly in children and young adults, with a peak incidence at ages 8-14 years.2,4 The lesion typically ranges in size from 1 to 5 cm, and is often present for years before removal, owing to its indolent growth characteristics.2 Gross and microscopic presentation Grossly, CAF is often a poorly defined, firm, white to gray tissue mass. The entity is usually ⬍3 cm at greatest diameter. Surrounding normal tissues, such as adipose, muscle, and connective tissue, may be incorporated within the lesion. In addition, mineralized material displaying a florid or focal pattern of distribution may be seen. Significant calcifications may be identified clinically upon palpation, with these areas corresponding to foci of gritty material noted at gross examination and sectioning of the specimen.4 Histologically, CAF is comprised of varying degrees of fibrous connective tissue arranged in a fascicular pattern. The lesion is bland in appearance and composed of plump spindle cells with round to ovoid nuclei with indistinct cell borders. The nuclei may be arranged
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Fig. 2. Diagnostic imaging. A, Panoramic radiograph reveals a mixed radiolucent radiopaque lesion overlying the left ascending ramus. B, Magnetic resonance imaging defines the lesion overlying the left ascending ramus. C, Axial and sagittal view of computerized tomographic scan with contrast demonstrates the mineralized component of the lesion and medial and lateral extent.
Fig. 3. Gross specimen. A, Gross examination of resection specimen shows a lobulated and circumscribed mass. A tendon attaches to, and is continuous with, the medial pole of the specimen. B, The sectioned specimen had a gritty consistency, and the tumor had a homogeneous white appearance.
in a palisading fashion. Extension of the fibrous connective tissue into the adjacent surrounding tissue is not uncommon.4 In addition, perivascular and perineuronal proliferations may arise within the stroma. Significantly, CAF may be found in association with a tendon or aponeurosis. Mitotic activity is not common, and cellular atypia is not observed. Calcification and cartilage formation may be identified in the latter phase of CAF development.4 The calcified component has been described as fine granules or large amorphous masses. Mature bone with hematopoietic elements are noted in the present case of CAF, representing an unusual form
of mineralization.2 The longstanding history of the lesion may explain such a finding. In addition, CAF may exhibit chondroid differentiation, with epitheliod fibroblasts and osteoclast-type giant cells.2 In the present lesion, distinct cartilage differentiation was not observed, although the stromal fibrous tissue had foci suggestive of fibrocartilage. Malignant transformation is very rare.5 Imaging Although CAF is a benign lesion, an infiltrative growth pattern is frequently observed. Radiographic
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Fig. 4. Histologic examination. A, Low-power view demonstrates fibrous connective tissue arranged in fascicles. B, Lesional tissue exhibiting tendon-like parallel arrangement of fibroblasts and collagen. C, Cellular focus of ovoid cells is present with a less collagenized stroma. D, A focus of osteoid exhibiting mineralization is evident within one of these more cellular aggregates. E, Bone with hematopoietic marrow surrounded by neoplastic fibrous connective tissue.
examination of CAF depicts a mass of varying radiodensity with calcific foci identified in regions corresponding to significant mineralization.4 Magnetic resonance imaging and computerized tomography are the imaging modalities of choice for CAF. Although radiographic imaging reveals a soft tissue mass with calcified foci, those findings are relatively nonspecific.6 Computerized tomography also depicts a soft tissue mass with calcifications. However, this imaging technique illustrates the infiltrative growth pattern of the lesion, because radial spread into the surrounding soft tissues can be clearly visualized.6 Magnetic resonance imaging shows CAF as a low-intensity tumor on T1and T2-weighted images, owing to the significant fibrous component.7 Importantly, such imaging allows
for strong heterogeneous enhancement which facilitates the identification of tumor borders and suggests the diagnosis of CAF when occurring in a common anatomic and clinical setting. Histologic examination is required for definitive diagnosis of CAF.6 Cytopathology as an adjunctive diagnostic aid A case diagnosed with cytology based on a fine needle aspiration biopsy (FNAB) has been reported.8 That case detailed the FNAB of a nontender mass between the fourth and fifth metacarpal bones in a 9-year-old boy. Findings included high cellularity consisting of bland spindle cells with small oval nuclei, fine chromatin, and smooth nuclear contours. In addition, a few chondroid cells were observed, as well as
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fragments of myxoid stroma, small blood vessels, and coarse calcified debris.8 Immunohistochemistry Although the lesion we describe in the present report was diagnosed without ancillary immunohistochemistry, several studies have examined CAF using various antibodies directed at specific antigens. In a review by Fetsch et al., all of the lesions examined (6 out of 6) were positive for vimentin, which was strong and diffuse. Muscle-specific actin and smooth muscle actin were each positive in one-half of the cases (3 out of 6), and CD99 was positive in all of the cases examined (5 out of 5). CD99 expression was greatest in spindle cells and detected focally in epitheliod fibroblasts and a few chondrocytes. S100 protein (5 out of 6) and CD68 (5 out of 5) were expressed in the majority of cases, and all of the tumors were negative for desmin and cytokeratins.2 Malignant transformation of CAF Although recurrences are common, malignant transformation is very rare. A single report described a primary CAF on the palm of a 3-year-old girl who eventually developed disseminated fibrosarcoma. Initially, this patient had a CAF removed with an incomplete margin of resection. When the child was 9 years old, she developed knee and shoulder pain. Chest radiographs revealed a mass occupying most of the right lung. Moreover, bony defects were seen throughout the body. The tumor was identified as a fibrosarcoma and the patient succumbed to her disease 3 months after diagnosis. The histopathology was reviewed at the Armed Forces Institute of Pathology, where it was concluded that the metastatic disease seemed to originate from the tumor of the left hand.5 Thus, although CAF is typically a benign process, careful long-term follow up is recommended, because there is a remote potential for malignant transformation. CONCLUSION In summary, we report the first case of CAF arising in a paracortical mandibular location. Although this
lesion followed an indolent course, it grew to a sizeable mass and required a significant surgical procedure. The authors acknowledge the following individuals for their generous provision of medical history, imaging studies, and photomicrographs: Drs. King Chong Chan, Barry Bass, and Edward Gabalski. REFERENCES 1. Keasbey LE. Juvenile aponeurotic fibroma (calcifying fibroma); a distinctive tumor arising in the palms and soles of young children. Cancer 1953;6:338-46. 2. Fetsch JF, Miettinen M. Calcifying aponeurotic fibroma: a clinicopathologic study of 22 cases arising in uncommon sites. Hum Pathol 1998;29:1504-10. 3. Yura S, Terahata S, Ohga N, Ooi K. A case of calcifying aponeurotic fibroma arising in the medial pterygoid muscle. J Oral Maxillofac Surg 2008;66:359-61. 4. Weiss SW. Goldblum JR. Enzinger & Weiss’s Soft Tissue Tumors. 5th ed. Philadelphia: Mosby Elsevier; 2008: pp 289-93. 5. Lafferty KA, Nelson EL, Demuth RJ, Miller SH, Harrison MW. Juvenile aponeurotic fibroma with disseminated fibrosarcoma. J Hand Surg Am 1986;11:737-40. 6. Hasegawa HK, Park S, Hamazaki M. Calcifying aponeurotic fibroma of the knee: a case report with radiological findings. J Dermatol 2006;33:169-73. 7. Kwak HS, Lee SY, Kim JR, Lee KB. MR imaging of calcifying aponeurotic fibroma of the thigh. Pediatr Radiol 2004;34:438-40. 8. Tai LH, Johnston JO, Klein HZ, Rowland J, Sudilovsky D. Calcifying aponeurotic fibroma features seen on fine-needle aspiration biopsy: case report and brief review of the literature. Diagn Cytopathol 2001;24:336-9. 9. Oruc M, Uysal A, Kankaya Y, Yildiz K, Aslan G, Sengul D. A case of calcifying aponeurotic fibroma of the scalp: case report and review of the literature. Dermatol Surg 2007;33:1380-3. 10. Sharma R, Punia RS, Sharma A, Marwah N. Juvenile (calcifying) aponeurotic fibroma of the neck. Pediatr Surg Int 1998;13: 295-6.
Reprint requests: John E. Fantasia, DDS Division of Oral and Maxillofacial Pathology Department of Dental Medicine Long Island Jewish Medical Center New Hyde Park, NY 11040 [email protected]
Aponeurotic fibroma (AF) was originally described by Keasbey in 1953 as juvenile aponeurotic fibroma, most commonly occurring in the distal extremities. Initially described in children and adolescents, AF is now recognized to occur over a wide age range and at various anatomic sites. A variant of this lesion, termed calcifying aponeurotic fibroma (CAF) has been described. CAF is a slow-growing, solitary, and painless nodule often adherent to tendon, fascia, or periosteum. We report a patient who presented with a firm lobulated mass, portions of which were fixed to the left ascending mandibular ramus. The lesion represented a CAF arising juxtacortical to the mandible, with the calcified component composed of mature bone exhibiting focal areas of hematopoiesis. Additional reports of CAF occurring in the head and neck region are reviewed. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2010;109:878-882)
Calcifying aponeurotic fibroma (CAF) was originally described by Keasbey in 1953 as a lesion in children which arises on the palms and soles,1 and has subsequently been described in other anatomic sites and occurring over a wide age range.2 Although CAF occurs primarily in the limbs, cases arising in the head and neck region are documented (Table I). The present report discusses a paracortical lesion of this type in the maxillofacial region and reviews the current literature on this rare entity. CASE REPORT A 62-year-old woman presented for evaluation of a progressively enlarging mass overlying the left ascending ramus and extending medially and laterally. The mass was visible on oral examination beneath the mucosa and was firm to palpation (Fig. 1). There was a history of biopsy of a small submucosal nodule in this same area 12 years earlier. The histopathology at that time was a descriptive diagnosis of oral mucosa with underlying loose fibrous connective tissue admixed with a few dilated endothelial lined channels; neoplasia was not identified in that biopsy. The clinical history and subsequent identification of the current mass suggested that representative tissue was not obtained. The lesion continued to enlarge slowly over the next 12 years, aaccording to patient history. There was no interval follow-up evaluation before establishing the diagnosis of CAF with biopsy. The patient’s
a
Resident, Oral and Maxillofacial Pathology. Resident, Oral and Maxillofacial Surgery. c Chief, Oral and Maxillofacial Pathology. The first two authors contributed equally to this work. Received for publication Jan 16, 2010; accepted for publication Jan 26, 2010. 1079-2104/$ - see front matter © 2010 Mosby, Inc. All rights reserved. doi:10.1016/j.tripleo.2010.01.020 b
878
medical history was significant for heart murmur, hypertension, hypercholesterolemia, and diabetes mellitus. She had a 40 pack-year history of cigarette smoking. The patient reported no known drug allergies, and her medications included quinaretic (Quinapril), nateglinide (Starlix), metoprolol (Toprol), metformin (Glucophage), simvastatin (Zocor), and aspirin. Clinically, the lesion presented as a submucosal swelling in the area of the left ascending ramus. The overlying mucosa was normal in color and not ulcerated. The clinical differential diagnoses included a wide variety of pathologic processes, including those of mesenchymal, neurogenic, and vascular origin. In addition, odontogenic and nonodontogenic processes, as well as a tumor of minor salivary gland or parotid gland were included in the differential diagnosis. A lymphoproliferative process was also considered, because of the location and size of the lesion. Imaging studies of the lesion demonstrated a soft tissue mass with calcifications without lytic changes to underlying bone (Fig. 2). Computerized tomographic scan of the lesion revealed an expansile mass of the left posterior mandible and ascending ramus with smooth cupping of medial ramus cortical bone. The lesion was well defined and lobulated and contained foci of ovoid to crescent-shaped bone. The mass extended to the intercondylar notch with lateral extension and possible displacement and compression of the left parotid duct. There was no infiltration into surrounding soft tissues, and no periosteal reaction was seen. Notably, the lesion was of sufficient size to compress the left posterior lateral tongue (Fig. 2, B). Upon imaging, the clinical differential was narrowed considerably, with the lesion appearing as a soft tissue mass with a mineralized component in a paracortical region of the left mandibular ramus. The radiographic differential diagnosis included lesions that may arise peripherally and cause bony erosion. Lesions with these characteristics in the maxillofacial region may include a peripheral calcifying epithelial odontogenic tumor, calcifying ghost cell odontogenic
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Table I. Cases of calcifying aponeurotic fibroma arising in the head and neck Case
Age (yrs)/ gender
Location
Size (cm)
Reference
1 2 3 4 5
6/M 60/F 3/M 5/F 62/F
Base of neck Medial pterygoid muscle Scalp Neck Juxtacortical to mandible
1 1 4 10 4.8
2 3 9 10 Present report
cytologic atypia were not observed. In some areas, a fibrocartilage-like pattern was seen, along with distinct bony islands. The histopathologic features were interpreted to be representative of CAF. This diagnosis was established with a generous biopsy and confirmed upon examination of the surgical excision. It is likely that this tumor represents the smaller mass described 12 years prior without the sampling of representative tissue. CAF grows slowly and rarely achieves the size documented here (Table I). Surgical excision is the recommended treatment for CAF. The current lesion was dissected from the surrounding tissues without difficulty; the adjacent mandibular bone was mechanically curetted. Local recurrences have been reported in 50% of patients for lesions reported at other anatomic sites.2 The patient continues to be followed-up at 3-month intervals and remained free of disease 1 year after surgery.
LITERATURE REVIEW
Fig. 1. Clinical presentation. The patient presented with a large submucosal nodule in her left ascending ramus. The nodule was firm to palpation, and the overlying mucosa was nonulcerated and normal in color.
cyst and tumor variants, giant cell granuloma, and salivary tumor with calcifications. To resect the lesion surgically, the patient was placed under general anesthesia and an incision made through the mucosa and submucosa along the left external oblique ridge of the mandible. At this time, the capsule of the lesion was clearly identified and appeared to be separate from the surrounding soft tissue except for a tendinous tract that appeared to be originating from the medial pterygoid muscle. Using a combination of blunt and sharp dissection, the lesion was carefully separated from the surrounding soft tissue and removed in its entirety as a single specimen. Upon examination, the lesion appeared as a large lobulated mass of tan soft tissue. A tendon was noted in continuity with the medial pole of the mass (Fig. 3). Upon sectioning, a firm gritty consistency was evident. Histologically, the lesion was composed of bland hypocellular to moderately cellular fibrous tissue with areas suggestive of a fibromatosis-like pattern as well as multiple circular foci of mature bone (Fig. 4). Some of the bone islands contained hematopoietic marrow. The fibrous tissue component demonstrated varying amounts of cellularity, with intervening dense collagenous stroma. Fibroblasts with round to ovoid nuclei were present (Fig. 4, C and D), and mitoses and
Clinical presentation Calcifying aponeurotic fibroma has classically been described as a nontender soft tissue neoplasm with a predilection for the proximal extremities. The lesion is most commonly found on the palms of the hands, soles of the feet and fingers, and less frequently occurs on ankles and wrists.1,2 A case of CAF arising in the medial pterygoid muscle has been reported;3 that patient presented with mild tenderness, and computerized tomography revealed a 1-cm calcifying mass.3 The lesion was dissected away from the muscle, and gross examination demonstrated the medial pterygoid tendon within the specimen.3 Although few cases of CAF are documented, it seems to have a male predominance, particularly in children and young adults, with a peak incidence at ages 8-14 years.2,4 The lesion typically ranges in size from 1 to 5 cm, and is often present for years before removal, owing to its indolent growth characteristics.2 Gross and microscopic presentation Grossly, CAF is often a poorly defined, firm, white to gray tissue mass. The entity is usually ⬍3 cm at greatest diameter. Surrounding normal tissues, such as adipose, muscle, and connective tissue, may be incorporated within the lesion. In addition, mineralized material displaying a florid or focal pattern of distribution may be seen. Significant calcifications may be identified clinically upon palpation, with these areas corresponding to foci of gritty material noted at gross examination and sectioning of the specimen.4 Histologically, CAF is comprised of varying degrees of fibrous connective tissue arranged in a fascicular pattern. The lesion is bland in appearance and composed of plump spindle cells with round to ovoid nuclei with indistinct cell borders. The nuclei may be arranged
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Kramer et al.
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Fig. 2. Diagnostic imaging. A, Panoramic radiograph reveals a mixed radiolucent radiopaque lesion overlying the left ascending ramus. B, Magnetic resonance imaging defines the lesion overlying the left ascending ramus. C, Axial and sagittal view of computerized tomographic scan with contrast demonstrates the mineralized component of the lesion and medial and lateral extent.
Fig. 3. Gross specimen. A, Gross examination of resection specimen shows a lobulated and circumscribed mass. A tendon attaches to, and is continuous with, the medial pole of the specimen. B, The sectioned specimen had a gritty consistency, and the tumor had a homogeneous white appearance.
in a palisading fashion. Extension of the fibrous connective tissue into the adjacent surrounding tissue is not uncommon.4 In addition, perivascular and perineuronal proliferations may arise within the stroma. Significantly, CAF may be found in association with a tendon or aponeurosis. Mitotic activity is not common, and cellular atypia is not observed. Calcification and cartilage formation may be identified in the latter phase of CAF development.4 The calcified component has been described as fine granules or large amorphous masses. Mature bone with hematopoietic elements are noted in the present case of CAF, representing an unusual form
of mineralization.2 The longstanding history of the lesion may explain such a finding. In addition, CAF may exhibit chondroid differentiation, with epitheliod fibroblasts and osteoclast-type giant cells.2 In the present lesion, distinct cartilage differentiation was not observed, although the stromal fibrous tissue had foci suggestive of fibrocartilage. Malignant transformation is very rare.5 Imaging Although CAF is a benign lesion, an infiltrative growth pattern is frequently observed. Radiographic
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Fig. 4. Histologic examination. A, Low-power view demonstrates fibrous connective tissue arranged in fascicles. B, Lesional tissue exhibiting tendon-like parallel arrangement of fibroblasts and collagen. C, Cellular focus of ovoid cells is present with a less collagenized stroma. D, A focus of osteoid exhibiting mineralization is evident within one of these more cellular aggregates. E, Bone with hematopoietic marrow surrounded by neoplastic fibrous connective tissue.
examination of CAF depicts a mass of varying radiodensity with calcific foci identified in regions corresponding to significant mineralization.4 Magnetic resonance imaging and computerized tomography are the imaging modalities of choice for CAF. Although radiographic imaging reveals a soft tissue mass with calcified foci, those findings are relatively nonspecific.6 Computerized tomography also depicts a soft tissue mass with calcifications. However, this imaging technique illustrates the infiltrative growth pattern of the lesion, because radial spread into the surrounding soft tissues can be clearly visualized.6 Magnetic resonance imaging shows CAF as a low-intensity tumor on T1and T2-weighted images, owing to the significant fibrous component.7 Importantly, such imaging allows
for strong heterogeneous enhancement which facilitates the identification of tumor borders and suggests the diagnosis of CAF when occurring in a common anatomic and clinical setting. Histologic examination is required for definitive diagnosis of CAF.6 Cytopathology as an adjunctive diagnostic aid A case diagnosed with cytology based on a fine needle aspiration biopsy (FNAB) has been reported.8 That case detailed the FNAB of a nontender mass between the fourth and fifth metacarpal bones in a 9-year-old boy. Findings included high cellularity consisting of bland spindle cells with small oval nuclei, fine chromatin, and smooth nuclear contours. In addition, a few chondroid cells were observed, as well as
882
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Kramer et al.
fragments of myxoid stroma, small blood vessels, and coarse calcified debris.8 Immunohistochemistry Although the lesion we describe in the present report was diagnosed without ancillary immunohistochemistry, several studies have examined CAF using various antibodies directed at specific antigens. In a review by Fetsch et al., all of the lesions examined (6 out of 6) were positive for vimentin, which was strong and diffuse. Muscle-specific actin and smooth muscle actin were each positive in one-half of the cases (3 out of 6), and CD99 was positive in all of the cases examined (5 out of 5). CD99 expression was greatest in spindle cells and detected focally in epitheliod fibroblasts and a few chondrocytes. S100 protein (5 out of 6) and CD68 (5 out of 5) were expressed in the majority of cases, and all of the tumors were negative for desmin and cytokeratins.2 Malignant transformation of CAF Although recurrences are common, malignant transformation is very rare. A single report described a primary CAF on the palm of a 3-year-old girl who eventually developed disseminated fibrosarcoma. Initially, this patient had a CAF removed with an incomplete margin of resection. When the child was 9 years old, she developed knee and shoulder pain. Chest radiographs revealed a mass occupying most of the right lung. Moreover, bony defects were seen throughout the body. The tumor was identified as a fibrosarcoma and the patient succumbed to her disease 3 months after diagnosis. The histopathology was reviewed at the Armed Forces Institute of Pathology, where it was concluded that the metastatic disease seemed to originate from the tumor of the left hand.5 Thus, although CAF is typically a benign process, careful long-term follow up is recommended, because there is a remote potential for malignant transformation. CONCLUSION In summary, we report the first case of CAF arising in a paracortical mandibular location. Although this
lesion followed an indolent course, it grew to a sizeable mass and required a significant surgical procedure. The authors acknowledge the following individuals for their generous provision of medical history, imaging studies, and photomicrographs: Drs. King Chong Chan, Barry Bass, and Edward Gabalski. REFERENCES 1. Keasbey LE. Juvenile aponeurotic fibroma (calcifying fibroma); a distinctive tumor arising in the palms and soles of young children. Cancer 1953;6:338-46. 2. Fetsch JF, Miettinen M. Calcifying aponeurotic fibroma: a clinicopathologic study of 22 cases arising in uncommon sites. Hum Pathol 1998;29:1504-10. 3. Yura S, Terahata S, Ohga N, Ooi K. A case of calcifying aponeurotic fibroma arising in the medial pterygoid muscle. J Oral Maxillofac Surg 2008;66:359-61. 4. Weiss SW. Goldblum JR. Enzinger & Weiss’s Soft Tissue Tumors. 5th ed. Philadelphia: Mosby Elsevier; 2008: pp 289-93. 5. Lafferty KA, Nelson EL, Demuth RJ, Miller SH, Harrison MW. Juvenile aponeurotic fibroma with disseminated fibrosarcoma. J Hand Surg Am 1986;11:737-40. 6. Hasegawa HK, Park S, Hamazaki M. Calcifying aponeurotic fibroma of the knee: a case report with radiological findings. J Dermatol 2006;33:169-73. 7. Kwak HS, Lee SY, Kim JR, Lee KB. MR imaging of calcifying aponeurotic fibroma of the thigh. Pediatr Radiol 2004;34:438-40. 8. Tai LH, Johnston JO, Klein HZ, Rowland J, Sudilovsky D. Calcifying aponeurotic fibroma features seen on fine-needle aspiration biopsy: case report and brief review of the literature. Diagn Cytopathol 2001;24:336-9. 9. Oruc M, Uysal A, Kankaya Y, Yildiz K, Aslan G, Sengul D. A case of calcifying aponeurotic fibroma of the scalp: case report and review of the literature. Dermatol Surg 2007;33:1380-3. 10. Sharma R, Punia RS, Sharma A, Marwah N. Juvenile (calcifying) aponeurotic fibroma of the neck. Pediatr Surg Int 1998;13: 295-6.
Reprint requests: John E. Fantasia, DDS Division of Oral and Maxillofacial Pathology Department of Dental Medicine Long Island Jewish Medical Center New Hyde Park, NY 11040 [email protected]