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Extraskeletal chondroma of the foot
Joint Bone Spine 74 (2007) 285e288 http://france.elsevier.com/direct/BONSOI/
Case report
Extraskeletal chondroma of the foot Panayiotis J. Papagelopoulos a,*, Olga D. Savvidou b, Andreas F. Mavrogenis a, George D. Chloros a, Kleo Th. Papaparaskeva c, Panayotis N. Soucacos a a
First Department of Orthopaedics, Athens University Medical School, 4 Christovassili Street, Neo Psychikon, 15451 Athens, Greece b Department of Orthopaedics, Thriasion Hospital, Elefsis, Greece c Division of Anatomic Pathology, Hygeia Athens Medical Center, Athens, Greece Received 3 March 2006; accepted 13 June 2006 Available online 27 February 2007
Abstract Benign extraskeletal chondromas are uncommon lesions with a predilection for the hands and the feet and can exhibit worrisome radiographic and histologic features mimicking chondrosarcomas. The authors present herein the case of a 74-year-old man with a painful mass at the dorsomedial aspect of the left foot. At 34 months after surgery the patient is disease-free with no evidence of recurrence. Ó 2007 Elsevier Masson SAS. All rights reserved. Keywords: Extraskeletal; Chondrosarcoma; Foot; Soft tissue tumors; Chondroma; Synovial chondromatosis
1. Introduction Extraskeletal chondroma or chondroma of the soft tissue is a relatively rare, benign, slow-growing soft tissue tumor that usually occurs in the hands and feet [1,2]. It may also be found in the joint capsules of the knee, elbow and other joints [3,4]. Extraskeletal chondroma probably arises from the fibrous stroma and not from mature cartilaginous or osseous tissue. It differs from juxtacortical or periosteal chondroma which is a benign tumor located between the bone and periosteum [5]. In this article a patient with extraskeletal chondroma of the foot is presented, with special attention to the imaging and clinicopathologic features. 2. Case report A 74-year-old man presented to the authors’ institution with a painful mass at the dorsomedial aspect of the left foot. Over the past 12 months the mass had enlarged in size and become more symptomatic (Fig. 1a,b). The patient had constant pain on ambulation. * Corresponding author. Tel./fax: þ30 210 672 1355. E-mail address: [email protected] (P.J. Papagelopoulos).
Physical examination showed a firm, tender, and somewhat fixed mass. The rest of the foot and ankle examination was within normal limits. Routine laboratory values were within normal limits. Plain radiographs of the right foot showed a soft tissue mass at the tarsometatalsal joints (Fig. 2a,b). Technetium bone scan showed increased radioisotope uptake at the tarsal bones of the left foot (Fig. 2c). Computed tomography scan showed a soft tissue mass at the dorsum of the foot, extending into the plantar soft tissues of the first and second tarsal bones, and the first and second metatarsals. There was erosion of the cortices of the first and second metatarsals (Fig. 3a,b). Magnetic resonance imaging showed a soft tissue mass located between the tarsal and the metatarsal bones of the left foot. The lesion was isointense to muscle on T1weighted images, and had high signal intensity on T2-weighted images (Fig. 4a,b). Open biopsy was performed. Histologic examination showed features of a chondroblastic neoplasm. There was mild atypia and cellularity. Differential diagnosis included chondroma and low grade chondrosarcoma. Surgical excision of the tumor was done. The lesion was encapsulated and was adherent to the extensor tendons sheaths. The mass was excised after meticulous dissection from the surrounding extensor tendons. In addition, multiple
1297-319X/$ - see front matter Ó 2007 Elsevier Masson SAS. All rights reserved. doi:10.1016/j.jbspin.2006.06.014
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P.J. Papagelopoulos et al. / Joint Bone Spine 74 (2007) 285e288
Fig. 3. Computed tomography scans of the left foot show (A) a soft tissue mass at the dorsum of the foot, and (B) extension of the mass into the plantar soft tissues, and erosion the cortices of the first and second metatarsals.
Fig. 1. (A,B) A 74-year-old man with a painful, enlarged mass at the dorsomedial aspect of the left foot. The patient had difficulty in walking and wearing his left shoe.
well-circumscribed cartilaginous nodules embedded in the synovium and loose in the tarsometatarsal joints were removed, consistent with associated synovial chondromatosis. The two lesions were clearly anatomically separated at surgery (Fig. S1a; see the supplementary material associated with this article online). Wound drainage was applied for 24 h and the patient was allowed partial weight bearing with crutches for 2 weeks. The size of the excised tumor was 7 5 3 cm. Histological examination showed a neoplasm composed predominantly of mature hyaline cartilage with variable cellularity and plump
Fig. 2. (A) Plain anteroposterior and (B) lateral radiographs of the left foot show a soft tissue mass at the tarsometatalsal joints. (C) Technetium bone scan showed increased radioisotope uptake at the tarsal and metatarsal bones of the left foot.
nuclei arranged in a lobular pattern at the periphery of the tumor (Fig. S1b). The islets of the hyaline cartilage were separated by richly vascularized interlobular connective tissue with extensive areas of fibrocartilaginous degeneration and myxoid changes. There were marked hyalinization, myxoid changes, and foci calcification of the tumor matrix. The tumor was surrounded by a fibrous pseudocapsule. Mild atypia without mitotic figures were present. The osteochondral loose bodies showed nodules of cartilage lined by synovial membranes and binucleate chondrocytes. The above histological findings were consistent with extraskeletal chondroma associated with synovial chondromatosis of the tarsometatarsal joints. At the latest follow-up, 34 months after the operation, the patient is asymptomatic. Magnetic resonance imaging shows no local recurrence of the tumor. 3. Discussion Several terms have been used to describe benign solitary cartilaginous masses in extrasynovial tissue including extraskeletal
Fig. 4. (A) T1-weighted magnetic resonance imaging show an isointense to muscle soft tissue mass located between the tarsal and the metatarsal bones of the left foot. (B) On T2-weighted images the lesion had high signal intensity.
P.J. Papagelopoulos et al. / Joint Bone Spine 74 (2007) 285e288
chondroma, extraosseous chondroma, tenosynovial chondroma, soft tissue chondroma, chondroma of the soft parts, and cartilaginous tumor of the soft tissue. The distinction between extraskeletal chondroma and synovial chondromatosis is usually made because the latter occurs in larger joints and is characterized by the formation of numerous, small, cartilaginous nodules within the synovium or an adjacent bursa [6] Extraskeletal chondroma is a relatively uncommon benign soft tissue tumor that usually occurs adjacent to periarticular tissues or tendosynovium, without any adhesion to the underlying bone [1,2,7], as in the present patient. The foot is the second most common location after the fingers, where more than 80% of the soft tissue chondromas are found [2,7]. Sporadic cases of extraskeletal chondromas have been reported in the dura, larynx, pharynx, oral cavity, parotid gland, and skin [7,8]. Most of the literature reports regarding extraskeletal chondromas consist of sporadic cases and small series. Dahlin and Salvador [9] in a series of 70 patients, and Chung and Enzinger [1] in a series of 104 patients confirmed the benign nature of these lesions, the predilection for the distal part of the extremities, and the variable histological appearance that is often confused with chondrosarcomas. Extraskeletal chondromas seem to originate from tendon sheaths, and unlike periosteal chondromas these tumors are located exterior to the periosteum [10]. Although some of the chondroblastic forms of extraskeletal chondromas may demonstrate atypical cellular features, there is no evidence that these tumors behave differently from the well-differentiated forms of mature hyaline cartilage. Cytogenetic data on soft tissue chondromas are limited. Clonal chromosomal abnormalities such as chromosome 6 monosomy and rearrangement of chromosome 11 have been identified [7]. Malignant transformation, although exceedingly rare has also been reported [2]. The tumor mainly affects 30e60-year-old adults. There is no gender predilection. The typical clinical presentation is that of a painless, slowly enlarging nodular soft tissue mass that is usually present for variable time prior to diagnosis. In approximately 20% of the patients, the lesion is painful and tender, especially if located in the plantar aspect of the foot [11e13]. Although bilateral extraskeletal chondromas have been reported [14], the overwhelming majority of extraskeletal chondromas are solitary. However, multiple lesions are more likely cases of synovial chondromatosis. The association of pulmonary chondroma, gastric epithelioid stromal tumor, and extra-adrenal paraganglioma is known as Carney’s triad [7]. The imaging features of extraskeletal chondromas depend on the amount of calcification and the response of the surrounding tissues. Approximately one-third of extraskeletal chondromas undergo focal calcification that is most often encountered in the center of the lesions [1,2,7,9]. Diffuse calcification is a late feature that may obscure the cartilaginous nature of these tumors [2]. Osseous changes are infrequent, although erosions, as seen in our patient and remodeling of the cortex may occur secondary to the soft tissue mass [15]. In the present patient, the computed tomography scans showed a calcified soft tissue mass that was entirely extraosseous. Magnetic resonance images showed a high signal intensity
287
mass on T2-weighted images. A homogeneous, predominantly high signal intensity lesion on T2-weighted images is a feature encountered in most neoplasms; this finding has no specificity and it is not especially suggestive of a benign cartilaginous mass [7,10,11]. Macroscopically, extraskeletal chondromas are usually lobulated, well-encapsulated, rubbery tumors [7]. The lesions are firm on palpation; however, if focal cystic degeneration has occurred, they may be soft and friable. The histological appearance may vary considerably but most often consists of well-encapsulated lobules of mature hyaline cartilage with varying cellularity [2,7]. The tumors may show focal or diffuse calcification, or ossification (osteochondromas), fibrosis (fibrochondromas), and myxoid changes (myxoid chondromas). Calcifications tend to be more pronounced in the center than at the periphery of the tumor lobules. Vascular fibrous capsules may be observed occasionally [12,15,16]. Hyaline cartilage-like lesions with fibrous pseudocapsule, as in the current patient, may also be observed. Chondroblastic variants, with immature cells, hyperchromatic nuclei, binucleated cells, and mitotic figures can also occur. The variable histologic appearance, particularly in the presence of myxoid changes may lead to the misdiagnosis of chondrosarcomas [2,7,15,16]. Akin to normal chondrocytes, the cells of the extraskeletal chondroma are positive for vimentin and S-100 protein [7]. Electron microscopy studies show chondrocytes with large indented nuclei, abundant rough endoplasmic reticulum and intermittent membrane-bound vacuoles. Short microvillous processes or filopodia extend from the cytoplasmic surfaces into the surrounding intercellular matrix. In calcified lesions, the latter contains variously sized aggregates of hydroxyapatite crystals [7]. The differential diagnosis of extraskeletal chondromas include synovial chondromatosis (usually multifocal), chondrosarcomas, periosteal or juxtacortical chondrosarcomas, synovial cell sarcomas, mature myositis ossificans, foreign body granulomas, angioliomyomas, calcified lipomas, and occasionally juxtacortical chondromyxoid fibromas, periosteal desmoid tumors, tumoral calcinosis and calcifying aponeurotic fibromas [2,7,15]. Extraskeletal chondromas and synovial chondromatosis have a similar anatomic distribution and tendency to present as a mass lesion overlying or adherent to tendon. However, extraskeletal chondromas tend to form a well-demarcated solitary mass, and have a somewhat younger age distribution with 58% of cases occurring between the ages of 10 and 39 years [17]. Synovial chondromatosis occurs in bigger joints, and is characterized by the formation of numerous, small, metaplastic cartilaginous or osseo-cartilaginous nodules of varying size attached to the synovium, the tendon sheaths, or the lining of the adjacent extra-articular bursa [7,17]. Histologically, both entities are constituted of mature hyaline cartilage with sometimes mild cellular atypia and undergo more or less calcification/ ossification [17]. However, because extraskeletal chondroma has substantially lower recurrence rate than synovial chondromatosis, the distinction between these two processes is clinically relevant [17]. The close proximity of a soft tissue chondroma and synovial chondromatosis in the case presented is very intriguing. It is
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clinically and histologically unclear whether these two lesions represented two different entities or a synovial chondromatosis with a ‘‘dominant’’, larger chondroma., as previously described [17]. Radiography usually distinguishes periosteal or juxtacortical chondroma from subungual osteochondroma. Periosteal or juxtacortical chondroma is a small well-circumscribed tumor located underneath the periosteum that erodes the underlying cortex with ‘‘ledges’’ or ‘‘buttresses’’ at the margin of the tumor, whereas subungual osteochondroma is a lesion with cartilage overlying well-developed bone [7]. Synovial sarcomas usually show spotty calcifications whereas extraskeletal chondromas usually show coarse calcification [4,7]. Marginal surgical excision is usually the treatment of choice with preservation of adjacent bone and soft tissue structures. Local recurrence rates up to 18% have been reported [3,10,14,15]. Recurrent tumors are best treated with re-excision [1,9].
Appendix A. Supplementary material Supplementary material (Fig. S1a,b) associated with this article can be found at http://www.sciencedirect.com, at doi 10.1016/j.jbspin.2006.06.014. References [1] Chung EB, Enzinger FM. Chondroma of soft parts. Cancer 1978;41: 1414e24. [2] Enzinger FM. Cartilaginous tumors and tumors like lesions of soft tissues. In: Enzinger FM, editor. Soft tissue tumors. St Louis: Mosby; 1983. p. 698e718.
[3] Bendall SP, Manners BT. Intracapsular chondroma of the knee. J South Orthop Assoc 1997;6:69e72. [4] Kudawara I, Ueda T, Araki N. Extraskeletal chondroma around the knee. Clin Radiol 2001;56:779e82. [5] Lewis MN, Kenan S, Yabut SM, Norman A, Steiner G. Periosteal chondroma. A report of ten cases and review of the literature. Clin Orthop 1990;526:185e92. [6] Folsom GJ, Lee DH, Lopez-Ben R, Winokur T, Jaffe KA. Hand mass in a 15-year-old boy. Clin Orthop 2003;412:269e75. [7] Weiss SW, Goldblum JR. In: Enzinger FM, Weiss SW, editors. Soft tissue tumors. 4th ed. St Louis: Mosby; 2001. p. 1361e8. [8] Aslam MB, Haqqani MT. Extraskeletal chondroma of parotid gland. Histopathology 2006;48:465e7. [9] Dahlin C, Salvador H. Cartilaginous tumors of the soft tissues of the hand and feet. Mayo Clin Proc 1974;49:721e6. [10] Nakamura R, Ehara S, Nishida J, Shiraishi H. Diffuse mineralization of extraskeletal chondroma: a case report. Radiat Med 1997;15:51e3. [11] Degryse HR, Aparisi F. Extraskeletal cartilaginous and osseous tumors. In: De Schepper AM, editor. Imaging of soft tissue tumors. Berlin: Springer-Verlag; 1997. p. 299e315. [12] Marcial-Seoane RA, Marcial-Seoane MA, Ramos E, Marcial-Rojas RA. Extraskeletal chondromas. Bol Asoc Med PR 1990;82:394e402. [13] Milgram JW, Dunn EJ. Para-articular chondromas and osteochondromas: a report of three cases. Clin Orthop 1980;148:147e51. [14] Dellon A, Weiss SW, Mitch WE. Bilateral extraosseous chondromas of the hand in a patient with chronic renal failure. Am Soc Surg Hand 1978;3:139e41. [15] O’Malley MJ, Faller GT, Craig CC. Extraskeletal chondroma of the foot. Orthopedics 1996;19:256e8. [16] Humphreys S, Pambakian H, McKee PH, Fletcher CDM. Soft tissue chondroma e a study of 15 tumors. Histopathology 1986;10:147e59. [17] Fetsch JF, Vinh TN, Remotti F, Walker EA, Murphey MD, Sweet DE. Tenosynovial (extraarticular) chondromatosis. An analysis of 37 cases of an underrecognized clinicopathologic entity with a strong predilection for the hands and feet and a high local recurrence rate. Am J Surg Pathol 2003;27:1260e8.
Case report
Extraskeletal chondroma of the foot Panayiotis J. Papagelopoulos a,*, Olga D. Savvidou b, Andreas F. Mavrogenis a, George D. Chloros a, Kleo Th. Papaparaskeva c, Panayotis N. Soucacos a a
First Department of Orthopaedics, Athens University Medical School, 4 Christovassili Street, Neo Psychikon, 15451 Athens, Greece b Department of Orthopaedics, Thriasion Hospital, Elefsis, Greece c Division of Anatomic Pathology, Hygeia Athens Medical Center, Athens, Greece Received 3 March 2006; accepted 13 June 2006 Available online 27 February 2007
Abstract Benign extraskeletal chondromas are uncommon lesions with a predilection for the hands and the feet and can exhibit worrisome radiographic and histologic features mimicking chondrosarcomas. The authors present herein the case of a 74-year-old man with a painful mass at the dorsomedial aspect of the left foot. At 34 months after surgery the patient is disease-free with no evidence of recurrence. Ó 2007 Elsevier Masson SAS. All rights reserved. Keywords: Extraskeletal; Chondrosarcoma; Foot; Soft tissue tumors; Chondroma; Synovial chondromatosis
1. Introduction Extraskeletal chondroma or chondroma of the soft tissue is a relatively rare, benign, slow-growing soft tissue tumor that usually occurs in the hands and feet [1,2]. It may also be found in the joint capsules of the knee, elbow and other joints [3,4]. Extraskeletal chondroma probably arises from the fibrous stroma and not from mature cartilaginous or osseous tissue. It differs from juxtacortical or periosteal chondroma which is a benign tumor located between the bone and periosteum [5]. In this article a patient with extraskeletal chondroma of the foot is presented, with special attention to the imaging and clinicopathologic features. 2. Case report A 74-year-old man presented to the authors’ institution with a painful mass at the dorsomedial aspect of the left foot. Over the past 12 months the mass had enlarged in size and become more symptomatic (Fig. 1a,b). The patient had constant pain on ambulation. * Corresponding author. Tel./fax: þ30 210 672 1355. E-mail address: [email protected] (P.J. Papagelopoulos).
Physical examination showed a firm, tender, and somewhat fixed mass. The rest of the foot and ankle examination was within normal limits. Routine laboratory values were within normal limits. Plain radiographs of the right foot showed a soft tissue mass at the tarsometatalsal joints (Fig. 2a,b). Technetium bone scan showed increased radioisotope uptake at the tarsal bones of the left foot (Fig. 2c). Computed tomography scan showed a soft tissue mass at the dorsum of the foot, extending into the plantar soft tissues of the first and second tarsal bones, and the first and second metatarsals. There was erosion of the cortices of the first and second metatarsals (Fig. 3a,b). Magnetic resonance imaging showed a soft tissue mass located between the tarsal and the metatarsal bones of the left foot. The lesion was isointense to muscle on T1weighted images, and had high signal intensity on T2-weighted images (Fig. 4a,b). Open biopsy was performed. Histologic examination showed features of a chondroblastic neoplasm. There was mild atypia and cellularity. Differential diagnosis included chondroma and low grade chondrosarcoma. Surgical excision of the tumor was done. The lesion was encapsulated and was adherent to the extensor tendons sheaths. The mass was excised after meticulous dissection from the surrounding extensor tendons. In addition, multiple
1297-319X/$ - see front matter Ó 2007 Elsevier Masson SAS. All rights reserved. doi:10.1016/j.jbspin.2006.06.014
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P.J. Papagelopoulos et al. / Joint Bone Spine 74 (2007) 285e288
Fig. 3. Computed tomography scans of the left foot show (A) a soft tissue mass at the dorsum of the foot, and (B) extension of the mass into the plantar soft tissues, and erosion the cortices of the first and second metatarsals.
Fig. 1. (A,B) A 74-year-old man with a painful, enlarged mass at the dorsomedial aspect of the left foot. The patient had difficulty in walking and wearing his left shoe.
well-circumscribed cartilaginous nodules embedded in the synovium and loose in the tarsometatarsal joints were removed, consistent with associated synovial chondromatosis. The two lesions were clearly anatomically separated at surgery (Fig. S1a; see the supplementary material associated with this article online). Wound drainage was applied for 24 h and the patient was allowed partial weight bearing with crutches for 2 weeks. The size of the excised tumor was 7 5 3 cm. Histological examination showed a neoplasm composed predominantly of mature hyaline cartilage with variable cellularity and plump
Fig. 2. (A) Plain anteroposterior and (B) lateral radiographs of the left foot show a soft tissue mass at the tarsometatalsal joints. (C) Technetium bone scan showed increased radioisotope uptake at the tarsal and metatarsal bones of the left foot.
nuclei arranged in a lobular pattern at the periphery of the tumor (Fig. S1b). The islets of the hyaline cartilage were separated by richly vascularized interlobular connective tissue with extensive areas of fibrocartilaginous degeneration and myxoid changes. There were marked hyalinization, myxoid changes, and foci calcification of the tumor matrix. The tumor was surrounded by a fibrous pseudocapsule. Mild atypia without mitotic figures were present. The osteochondral loose bodies showed nodules of cartilage lined by synovial membranes and binucleate chondrocytes. The above histological findings were consistent with extraskeletal chondroma associated with synovial chondromatosis of the tarsometatarsal joints. At the latest follow-up, 34 months after the operation, the patient is asymptomatic. Magnetic resonance imaging shows no local recurrence of the tumor. 3. Discussion Several terms have been used to describe benign solitary cartilaginous masses in extrasynovial tissue including extraskeletal
Fig. 4. (A) T1-weighted magnetic resonance imaging show an isointense to muscle soft tissue mass located between the tarsal and the metatarsal bones of the left foot. (B) On T2-weighted images the lesion had high signal intensity.
P.J. Papagelopoulos et al. / Joint Bone Spine 74 (2007) 285e288
chondroma, extraosseous chondroma, tenosynovial chondroma, soft tissue chondroma, chondroma of the soft parts, and cartilaginous tumor of the soft tissue. The distinction between extraskeletal chondroma and synovial chondromatosis is usually made because the latter occurs in larger joints and is characterized by the formation of numerous, small, cartilaginous nodules within the synovium or an adjacent bursa [6] Extraskeletal chondroma is a relatively uncommon benign soft tissue tumor that usually occurs adjacent to periarticular tissues or tendosynovium, without any adhesion to the underlying bone [1,2,7], as in the present patient. The foot is the second most common location after the fingers, where more than 80% of the soft tissue chondromas are found [2,7]. Sporadic cases of extraskeletal chondromas have been reported in the dura, larynx, pharynx, oral cavity, parotid gland, and skin [7,8]. Most of the literature reports regarding extraskeletal chondromas consist of sporadic cases and small series. Dahlin and Salvador [9] in a series of 70 patients, and Chung and Enzinger [1] in a series of 104 patients confirmed the benign nature of these lesions, the predilection for the distal part of the extremities, and the variable histological appearance that is often confused with chondrosarcomas. Extraskeletal chondromas seem to originate from tendon sheaths, and unlike periosteal chondromas these tumors are located exterior to the periosteum [10]. Although some of the chondroblastic forms of extraskeletal chondromas may demonstrate atypical cellular features, there is no evidence that these tumors behave differently from the well-differentiated forms of mature hyaline cartilage. Cytogenetic data on soft tissue chondromas are limited. Clonal chromosomal abnormalities such as chromosome 6 monosomy and rearrangement of chromosome 11 have been identified [7]. Malignant transformation, although exceedingly rare has also been reported [2]. The tumor mainly affects 30e60-year-old adults. There is no gender predilection. The typical clinical presentation is that of a painless, slowly enlarging nodular soft tissue mass that is usually present for variable time prior to diagnosis. In approximately 20% of the patients, the lesion is painful and tender, especially if located in the plantar aspect of the foot [11e13]. Although bilateral extraskeletal chondromas have been reported [14], the overwhelming majority of extraskeletal chondromas are solitary. However, multiple lesions are more likely cases of synovial chondromatosis. The association of pulmonary chondroma, gastric epithelioid stromal tumor, and extra-adrenal paraganglioma is known as Carney’s triad [7]. The imaging features of extraskeletal chondromas depend on the amount of calcification and the response of the surrounding tissues. Approximately one-third of extraskeletal chondromas undergo focal calcification that is most often encountered in the center of the lesions [1,2,7,9]. Diffuse calcification is a late feature that may obscure the cartilaginous nature of these tumors [2]. Osseous changes are infrequent, although erosions, as seen in our patient and remodeling of the cortex may occur secondary to the soft tissue mass [15]. In the present patient, the computed tomography scans showed a calcified soft tissue mass that was entirely extraosseous. Magnetic resonance images showed a high signal intensity
287
mass on T2-weighted images. A homogeneous, predominantly high signal intensity lesion on T2-weighted images is a feature encountered in most neoplasms; this finding has no specificity and it is not especially suggestive of a benign cartilaginous mass [7,10,11]. Macroscopically, extraskeletal chondromas are usually lobulated, well-encapsulated, rubbery tumors [7]. The lesions are firm on palpation; however, if focal cystic degeneration has occurred, they may be soft and friable. The histological appearance may vary considerably but most often consists of well-encapsulated lobules of mature hyaline cartilage with varying cellularity [2,7]. The tumors may show focal or diffuse calcification, or ossification (osteochondromas), fibrosis (fibrochondromas), and myxoid changes (myxoid chondromas). Calcifications tend to be more pronounced in the center than at the periphery of the tumor lobules. Vascular fibrous capsules may be observed occasionally [12,15,16]. Hyaline cartilage-like lesions with fibrous pseudocapsule, as in the current patient, may also be observed. Chondroblastic variants, with immature cells, hyperchromatic nuclei, binucleated cells, and mitotic figures can also occur. The variable histologic appearance, particularly in the presence of myxoid changes may lead to the misdiagnosis of chondrosarcomas [2,7,15,16]. Akin to normal chondrocytes, the cells of the extraskeletal chondroma are positive for vimentin and S-100 protein [7]. Electron microscopy studies show chondrocytes with large indented nuclei, abundant rough endoplasmic reticulum and intermittent membrane-bound vacuoles. Short microvillous processes or filopodia extend from the cytoplasmic surfaces into the surrounding intercellular matrix. In calcified lesions, the latter contains variously sized aggregates of hydroxyapatite crystals [7]. The differential diagnosis of extraskeletal chondromas include synovial chondromatosis (usually multifocal), chondrosarcomas, periosteal or juxtacortical chondrosarcomas, synovial cell sarcomas, mature myositis ossificans, foreign body granulomas, angioliomyomas, calcified lipomas, and occasionally juxtacortical chondromyxoid fibromas, periosteal desmoid tumors, tumoral calcinosis and calcifying aponeurotic fibromas [2,7,15]. Extraskeletal chondromas and synovial chondromatosis have a similar anatomic distribution and tendency to present as a mass lesion overlying or adherent to tendon. However, extraskeletal chondromas tend to form a well-demarcated solitary mass, and have a somewhat younger age distribution with 58% of cases occurring between the ages of 10 and 39 years [17]. Synovial chondromatosis occurs in bigger joints, and is characterized by the formation of numerous, small, metaplastic cartilaginous or osseo-cartilaginous nodules of varying size attached to the synovium, the tendon sheaths, or the lining of the adjacent extra-articular bursa [7,17]. Histologically, both entities are constituted of mature hyaline cartilage with sometimes mild cellular atypia and undergo more or less calcification/ ossification [17]. However, because extraskeletal chondroma has substantially lower recurrence rate than synovial chondromatosis, the distinction between these two processes is clinically relevant [17]. The close proximity of a soft tissue chondroma and synovial chondromatosis in the case presented is very intriguing. It is
288
P.J. Papagelopoulos et al. / Joint Bone Spine 74 (2007) 285e288
clinically and histologically unclear whether these two lesions represented two different entities or a synovial chondromatosis with a ‘‘dominant’’, larger chondroma., as previously described [17]. Radiography usually distinguishes periosteal or juxtacortical chondroma from subungual osteochondroma. Periosteal or juxtacortical chondroma is a small well-circumscribed tumor located underneath the periosteum that erodes the underlying cortex with ‘‘ledges’’ or ‘‘buttresses’’ at the margin of the tumor, whereas subungual osteochondroma is a lesion with cartilage overlying well-developed bone [7]. Synovial sarcomas usually show spotty calcifications whereas extraskeletal chondromas usually show coarse calcification [4,7]. Marginal surgical excision is usually the treatment of choice with preservation of adjacent bone and soft tissue structures. Local recurrence rates up to 18% have been reported [3,10,14,15]. Recurrent tumors are best treated with re-excision [1,9].
Appendix A. Supplementary material Supplementary material (Fig. S1a,b) associated with this article can be found at http://www.sciencedirect.com, at doi 10.1016/j.jbspin.2006.06.014. References [1] Chung EB, Enzinger FM. Chondroma of soft parts. Cancer 1978;41: 1414e24. [2] Enzinger FM. Cartilaginous tumors and tumors like lesions of soft tissues. In: Enzinger FM, editor. Soft tissue tumors. St Louis: Mosby; 1983. p. 698e718.
[3] Bendall SP, Manners BT. Intracapsular chondroma of the knee. J South Orthop Assoc 1997;6:69e72. [4] Kudawara I, Ueda T, Araki N. Extraskeletal chondroma around the knee. Clin Radiol 2001;56:779e82. [5] Lewis MN, Kenan S, Yabut SM, Norman A, Steiner G. Periosteal chondroma. A report of ten cases and review of the literature. Clin Orthop 1990;526:185e92. [6] Folsom GJ, Lee DH, Lopez-Ben R, Winokur T, Jaffe KA. Hand mass in a 15-year-old boy. Clin Orthop 2003;412:269e75. [7] Weiss SW, Goldblum JR. In: Enzinger FM, Weiss SW, editors. Soft tissue tumors. 4th ed. St Louis: Mosby; 2001. p. 1361e8. [8] Aslam MB, Haqqani MT. Extraskeletal chondroma of parotid gland. Histopathology 2006;48:465e7. [9] Dahlin C, Salvador H. Cartilaginous tumors of the soft tissues of the hand and feet. Mayo Clin Proc 1974;49:721e6. [10] Nakamura R, Ehara S, Nishida J, Shiraishi H. Diffuse mineralization of extraskeletal chondroma: a case report. Radiat Med 1997;15:51e3. [11] Degryse HR, Aparisi F. Extraskeletal cartilaginous and osseous tumors. In: De Schepper AM, editor. Imaging of soft tissue tumors. Berlin: Springer-Verlag; 1997. p. 299e315. [12] Marcial-Seoane RA, Marcial-Seoane MA, Ramos E, Marcial-Rojas RA. Extraskeletal chondromas. Bol Asoc Med PR 1990;82:394e402. [13] Milgram JW, Dunn EJ. Para-articular chondromas and osteochondromas: a report of three cases. Clin Orthop 1980;148:147e51. [14] Dellon A, Weiss SW, Mitch WE. Bilateral extraosseous chondromas of the hand in a patient with chronic renal failure. Am Soc Surg Hand 1978;3:139e41. [15] O’Malley MJ, Faller GT, Craig CC. Extraskeletal chondroma of the foot. Orthopedics 1996;19:256e8. [16] Humphreys S, Pambakian H, McKee PH, Fletcher CDM. Soft tissue chondroma e a study of 15 tumors. Histopathology 1986;10:147e59. [17] Fetsch JF, Vinh TN, Remotti F, Walker EA, Murphey MD, Sweet DE. Tenosynovial (extraarticular) chondromatosis. An analysis of 37 cases of an underrecognized clinicopathologic entity with a strong predilection for the hands and feet and a high local recurrence rate. Am J Surg Pathol 2003;27:1260e8.