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Spontaneous regression of a solitary osteochondroma of the distal tibia
J Orthop Sci (2009) 14:669–671 DOI 10.1007/s00776-009-1362-7
Case report Spontaneous regression of a solitary osteochondroma of the distal tibia SHINJI MINAMI, NAOKI NAKATANI, NOBUYUKI MIYAZAKI, ATSUNORI WATANUKI, TAKAKI HONDA, and MUNEHITO YOSHIDA Department of Orthopedic Surgery, Wakayama Medical University, 811-1 Kimiidera, Wakayama 641-8510, Japan
Introduction Osteochondroma is a common benign bone tumor. The tumor comprises almost 35% of all primary benign bone tumors and 8% of all bone tumors.1 The tumor usually arises from the metaphysis of a tubular bone. It has been reported that osteochondromas occur during childhood, and the lesion may stop growing at any time; however, in most cases, an osteochondroma stops growing at the cessation of normal skeletal growth.2,3 Although malignant transformation secondary to a solitary osteochondroma has been reported, the incidence of malignant transformation is less than 1% in cases of solitary osteochondroma.4 Regression or absorption of this tumor is a rare event. Only 17 cases of regressed solitary osteochondroma have been reported.5–20 Regressed osteochondromas have been seen in the proximal humerus and distal femur in most cases5 and was observed in the distal tibia in only one case.6 Magnetic resonance imaging (MRI) analysis of a regressed osteochondroma has been reported in only one case, and the osteochondroma did not have a cartilage cap on the initial MRI scan.7 In this report, we present a case of spontaneous regression of a solitary osteochondroma arising in the distal part of the tibia with emphasis placed on the MRI findings. We discuss the mechanism of this phenomenon. The patient and her parents were informed that her data would be submitted for publication and gave consent.
Case report A 6-year-old girl noticed a painless mass in the left distal tibia. She had visited a local clinic, and a bone Offprint requests to: S. Minami Received: December 21, 2008 / Accepted: March 3, 2009
tumor of the distal tibia was noted. She was then admitted to our hospital. She had no history of trauma, pain or fever. Clinical examination revealed a painless, hard, smooth surface, nontender, nonmobile mass on the anterior aspect of the left distal tibia. There was no restriction of ankle motion. Radiographs showed an exophytic bone lesion in the distal tibia that had continuity with the medullary cavity (Fig. 1). MRI demonstrated a tumor in continuity with the medullary cavity. On the T1-weighted image, a region of isointense signal, compared with the intensity of the muscle, was recognized on the surface of the tumor in continuity with the growth plate (Fig. 2a). On the T2-weighted image, the region demonstrated high signal intensity compared with the muscle; it was 0.25 cm in the thickest part and partially defective (Fig. 2b). There was no clinical or radiographic evidence of multiple hereditary osteochondromas. We diagnosed the tumor as a solitary sessile osteochondroma. The patient was asymptomatic and continued to be monitored without any treatment. Ten months after the initial diagnosis, radiographs showed gradual regression of the tumor (Fig. 3). Two years after the initial diagnosis, plain radiography showed complete regression of the tumor (Fig. 4), and the tumor was no longer detected by MRI (Fig. 5).
Discussion In 1835, Hunter first described spontaneous regression of an osteochondroma,21 and some isolated cases have since been reported. A computer-based literature search revealed 17 cases of regressed solitary osteochondroma, excluding cases of multiple hereditary osteochondromatosis. Of these 17 cases, 14 were reviewed by Arkader et al. in 2007,5 and an additional three cases were reported by Choi et al.,7 Hoshi et al.,8 and Yasuda et al.6 Among these 17 cases, the average age at diagnosis and
670
S. Minami et al.: Regression of osteochondroma
Fig. 1. Radiograph of the left distal tibia obtained on admission. Radiograph shows an exophytic bone lesion in the distal tibia. The tumor had continuity with the medullary cavity, and the surface of the tumor was irregular
a
Fig. 4. Radiograph of the left distal tibia obtained 2 years after the initial diagnosis shows complete regression of the tumor
b
Fig. 2. a Sagittal T1-weighted magnetic resonance imaging (MRI) (TR 502 ms, TE 14 ms) scan of the left distal tibia obtained on admission. It shows a tumor in continuity with the medullary cavity and an isointensity region on its surface. The region had continuity with the growth plate. b Sagittal T2-weighted MRI (TR 3500 ms, TE 90 ms) of the left distal tibia obtained on admission. MRI showed very high signal intensity of the region on the tumor surface. This region was partially defective
Fig. 3. Radiograph of the left distal tibia obtained 10 months after the initial diagnosis. The tumor surface had become smooth, and the tumor had gradually regressed
Fig. 5. Sagittal T2-weighted MRI (TR 5000 ms, TE 90 ms) scan obtained 2 years after the initial diagnosis on which the tumor could no longer be detected
regression was 7.8 years (range 1.7–15 years) and 11.1 years (range 4.2–19 years), respectively. The age at diagnosis of a regressed solitary osteochondroma was 15 years in only one case and younger than 12 years in the other cases. A completely regressed osteochondroma was most commonly seen in the proximal humerus (6/17), and the distal femur (4/17); only one case was in the distal tibia, as in our case.6 Regression of an osteochondroma was recognized in 13 cases of the sessile type and 4 cases of the pedunculated type. The sessile-type osteochondroma therefore regressed more frequently than the pedunculated type. Two hypotheses have been proposed concerning the regression mechanism of this tumor.9–11 Copeland et al.9 and Castriota-Scanderbeg et al.10 proposed that the active resorption and metaphysical remodeling caused by altered vascular supply due to fracture may lead to cessation of the cartilage cap and subsequent tumor regression.9,10 The pedunculated-type osteochondroma could be applied to their theory; the vascular supply was interrupted with stalk fracture and the lesion conse-
S. Minami et al.: Regression of osteochondroma
quently regressed. Paling proposed that osteochondroma growth ceases before somatic growth ceases, followed by incorporation of the osteochondroma into the cortex by appositional growth of the adjacent bone.11 In our case, there was no history of antecedent trauma or clinical features suggesting fracture; therefore, it was easier to apply Paling’s theory to our case for the mechanism of tumor regression; that is, tumor growth ceased, and the tumor subsequently regressed. Magnetic resonance imaging analysis of a regressed osteochondroma has been reported in only one case, and the osteochondroma did not have a cartilage cap at the initial MRI.7 It is reported that the cartilage cap of an osteochondroma is prematurely ossified,7 and tumor growth ceases by the time of skeletal maturation. In our case, a region on the surface of the tumor that was continuous with the growth plate was noted. The region demonstrated very high signal intensity on the T2weighted image and was 0.25 cm in the thickest part and partially defective. At first, this was thought to be the cartilage cap because the region was continuous with the growth plate; however, the region demonstrated higher signal intensity than the growth plate or ankle joint cartilage on the T2-weighted image. Because the signal intensity of the region was very high, it could have been the bursa rather than the cartilage cap; however, this dilemma could not be clarified by MRI. If this region was the cartilage cap, it might have gradually disappeared because it was partially defective. If the very high signal intensity region was the bursa, the cartilage cap might already have disappeared or become very thin. Dahlin pointed out that an osteochondroma that has stopped growing has practically no cartilage in the cap.22 In our case, it was unknown whether the cartilage cap of the osteochondroma had already prematurely ossified. It is reported that most patients with regressed osteochondroma are less than 12 years old at the time of diagnosis5; therefore, if the cartilage cap is not detected by MRI, tumor growth might have ceased, and subsequently tumor regression might have occurred by the time of skeletal maturation.
Conclusion We present a case of spontaneous regression of solitary osteochondroma. T2-weighted MRI imaging demonstrated a very high signal intensity region on the tumor surface that was continuous with the growth plate and partially defective. The region was thought to be the cartilage cap or bursa, and the cartilage cap might already have disappeared or become very thin. If the
671
cartilage cap was not detected on follow-up MRI, tumor growth might have ceased, and the osteochondroma might have regressed by the time of skeletal maturation.
References 1. Fletcher CDM, Unni KK, Merteus F. WHO classification of tumors of soft tissue and bone. Lyon: IARC Press; 2002. 2. Harsha WN. The natural history of osteocartilaginous exostosis (osteochondroma). Am Surg 1954;20:65–72. 3. Jaffe HL. Tumors and tumorous conditions of the bones and joints. Philadelphia: Lea & Febiger; 1958. p. 143–67. 4. Campanacci M. Bone and soft tissue tumors. 2nd edn. Wien New York and Piccin Padova: Springer-Verlag; 1999. 5. Arkader A, Dormans JP, Gaugler R, Davidson RS. Spontaneous regression of solitary osteochondroma: reconsidering our approach. Clin Orthop 2007;460:253–7. 6. Yasuda H, Ieguchi M, Hoshi M, Taguchi S, Aono K, Takaoka K. Spontaneous regression of exostosis of tibia: a case report. Cent Jpn J Orthop Traumatol 2008;51;67–8 (in Japanese). 7. Choi JY, Hong SH, Kim HS, Chang CB, Lee YJ, Kang HS. Resorption of osteochondroma by accompanying pseudoaneurysm. AJR Am J Roentgenol 2005;185:394–6. 8. Hoshi M, Takami M, Hashimoto R, Okamoto T, Yanagida I, Matsumura A, et al. Spontaneous regression of osteochondromas. Skeletal Radiol 2007;36:531–4. 9. Copeland RL, Meehan PL, Morrissy RT. Spontaneous regression of osteochondromas: two case reports. J Bone Joint Surg Am 1985;67:971–3. 10. Castriota-Scanderbeg A, Bonetti MG, Cammisa M, Dallapiccola B. Spontaneous regression of exostoses: two case reports. Radiology 1995;25:544–8. 11. Paling MR. The “disappearing” osteochondroma. Skeletal Radiol 1983;10:40–2. 12. Sellink JL. Spontaneous regression of an exostosis. J Belge Radiol 1960;43:177–9. 13. Callan JE, Wood VE, Linda L. Spontaneous resolution of an osteochondroma. J Bone Joint Surg Am 1975;57:723–5. 14. Merle P, Rougier JL, Duclos AM, Gras JC. Evanescent exostosis: a report on one case. J Radiol 1980;61:291–2 (author’s translation). 15. Montgomery DM, LaMont RL. Resolving,solitary osteochondromas: a report of two cases and literature review. Orthopedics 1989;12:861–3. 16. Claikens B, Brys P, Samson I, Baert AL. Spontaneous resolution of a solitary osteochondroma. Skeletal Radiol 1998;27:53–5. 17. Revilla Y, Lozano MC, González G, Martínez A. Evanescent exostosis: a new case. Eur J Radiol 1999;29:270–2. 18. Yamamoto T, Kurosaka M, Mizuno K. Spontaneous resolution of a phalangeal solitary osteochondroma. J Hand Surg [Am] 2001;26:556–8. 19. Yanagawa T, Watanabe H, Shinozaki T, Ahmed AR, Shirakura K, Takagishi K. The natural history of disappearing bone tumours and tumour-like conditions. Clin Radiol 2001;56:877–86. 20. Reston SC, Savva N, Richards RH. Spontaneous resolution of solitary osteochondroma in the young adult. Skeletal Radiol 2004;33:303–5. 21. Hunter J. The works of John Hunter, with notes by JF Palmar. London: Longmans; 1835. p. 533–4. 22. Dahlin DC. Bone Tumors: general aspects and data on 6221 cases. 3rd edn. Springfield, IL: Charles C Thomas; 1978. p. 18–27.
Case report Spontaneous regression of a solitary osteochondroma of the distal tibia SHINJI MINAMI, NAOKI NAKATANI, NOBUYUKI MIYAZAKI, ATSUNORI WATANUKI, TAKAKI HONDA, and MUNEHITO YOSHIDA Department of Orthopedic Surgery, Wakayama Medical University, 811-1 Kimiidera, Wakayama 641-8510, Japan
Introduction Osteochondroma is a common benign bone tumor. The tumor comprises almost 35% of all primary benign bone tumors and 8% of all bone tumors.1 The tumor usually arises from the metaphysis of a tubular bone. It has been reported that osteochondromas occur during childhood, and the lesion may stop growing at any time; however, in most cases, an osteochondroma stops growing at the cessation of normal skeletal growth.2,3 Although malignant transformation secondary to a solitary osteochondroma has been reported, the incidence of malignant transformation is less than 1% in cases of solitary osteochondroma.4 Regression or absorption of this tumor is a rare event. Only 17 cases of regressed solitary osteochondroma have been reported.5–20 Regressed osteochondromas have been seen in the proximal humerus and distal femur in most cases5 and was observed in the distal tibia in only one case.6 Magnetic resonance imaging (MRI) analysis of a regressed osteochondroma has been reported in only one case, and the osteochondroma did not have a cartilage cap on the initial MRI scan.7 In this report, we present a case of spontaneous regression of a solitary osteochondroma arising in the distal part of the tibia with emphasis placed on the MRI findings. We discuss the mechanism of this phenomenon. The patient and her parents were informed that her data would be submitted for publication and gave consent.
Case report A 6-year-old girl noticed a painless mass in the left distal tibia. She had visited a local clinic, and a bone Offprint requests to: S. Minami Received: December 21, 2008 / Accepted: March 3, 2009
tumor of the distal tibia was noted. She was then admitted to our hospital. She had no history of trauma, pain or fever. Clinical examination revealed a painless, hard, smooth surface, nontender, nonmobile mass on the anterior aspect of the left distal tibia. There was no restriction of ankle motion. Radiographs showed an exophytic bone lesion in the distal tibia that had continuity with the medullary cavity (Fig. 1). MRI demonstrated a tumor in continuity with the medullary cavity. On the T1-weighted image, a region of isointense signal, compared with the intensity of the muscle, was recognized on the surface of the tumor in continuity with the growth plate (Fig. 2a). On the T2-weighted image, the region demonstrated high signal intensity compared with the muscle; it was 0.25 cm in the thickest part and partially defective (Fig. 2b). There was no clinical or radiographic evidence of multiple hereditary osteochondromas. We diagnosed the tumor as a solitary sessile osteochondroma. The patient was asymptomatic and continued to be monitored without any treatment. Ten months after the initial diagnosis, radiographs showed gradual regression of the tumor (Fig. 3). Two years after the initial diagnosis, plain radiography showed complete regression of the tumor (Fig. 4), and the tumor was no longer detected by MRI (Fig. 5).
Discussion In 1835, Hunter first described spontaneous regression of an osteochondroma,21 and some isolated cases have since been reported. A computer-based literature search revealed 17 cases of regressed solitary osteochondroma, excluding cases of multiple hereditary osteochondromatosis. Of these 17 cases, 14 were reviewed by Arkader et al. in 2007,5 and an additional three cases were reported by Choi et al.,7 Hoshi et al.,8 and Yasuda et al.6 Among these 17 cases, the average age at diagnosis and
670
S. Minami et al.: Regression of osteochondroma
Fig. 1. Radiograph of the left distal tibia obtained on admission. Radiograph shows an exophytic bone lesion in the distal tibia. The tumor had continuity with the medullary cavity, and the surface of the tumor was irregular
a
Fig. 4. Radiograph of the left distal tibia obtained 2 years after the initial diagnosis shows complete regression of the tumor
b
Fig. 2. a Sagittal T1-weighted magnetic resonance imaging (MRI) (TR 502 ms, TE 14 ms) scan of the left distal tibia obtained on admission. It shows a tumor in continuity with the medullary cavity and an isointensity region on its surface. The region had continuity with the growth plate. b Sagittal T2-weighted MRI (TR 3500 ms, TE 90 ms) of the left distal tibia obtained on admission. MRI showed very high signal intensity of the region on the tumor surface. This region was partially defective
Fig. 3. Radiograph of the left distal tibia obtained 10 months after the initial diagnosis. The tumor surface had become smooth, and the tumor had gradually regressed
Fig. 5. Sagittal T2-weighted MRI (TR 5000 ms, TE 90 ms) scan obtained 2 years after the initial diagnosis on which the tumor could no longer be detected
regression was 7.8 years (range 1.7–15 years) and 11.1 years (range 4.2–19 years), respectively. The age at diagnosis of a regressed solitary osteochondroma was 15 years in only one case and younger than 12 years in the other cases. A completely regressed osteochondroma was most commonly seen in the proximal humerus (6/17), and the distal femur (4/17); only one case was in the distal tibia, as in our case.6 Regression of an osteochondroma was recognized in 13 cases of the sessile type and 4 cases of the pedunculated type. The sessile-type osteochondroma therefore regressed more frequently than the pedunculated type. Two hypotheses have been proposed concerning the regression mechanism of this tumor.9–11 Copeland et al.9 and Castriota-Scanderbeg et al.10 proposed that the active resorption and metaphysical remodeling caused by altered vascular supply due to fracture may lead to cessation of the cartilage cap and subsequent tumor regression.9,10 The pedunculated-type osteochondroma could be applied to their theory; the vascular supply was interrupted with stalk fracture and the lesion conse-
S. Minami et al.: Regression of osteochondroma
quently regressed. Paling proposed that osteochondroma growth ceases before somatic growth ceases, followed by incorporation of the osteochondroma into the cortex by appositional growth of the adjacent bone.11 In our case, there was no history of antecedent trauma or clinical features suggesting fracture; therefore, it was easier to apply Paling’s theory to our case for the mechanism of tumor regression; that is, tumor growth ceased, and the tumor subsequently regressed. Magnetic resonance imaging analysis of a regressed osteochondroma has been reported in only one case, and the osteochondroma did not have a cartilage cap at the initial MRI.7 It is reported that the cartilage cap of an osteochondroma is prematurely ossified,7 and tumor growth ceases by the time of skeletal maturation. In our case, a region on the surface of the tumor that was continuous with the growth plate was noted. The region demonstrated very high signal intensity on the T2weighted image and was 0.25 cm in the thickest part and partially defective. At first, this was thought to be the cartilage cap because the region was continuous with the growth plate; however, the region demonstrated higher signal intensity than the growth plate or ankle joint cartilage on the T2-weighted image. Because the signal intensity of the region was very high, it could have been the bursa rather than the cartilage cap; however, this dilemma could not be clarified by MRI. If this region was the cartilage cap, it might have gradually disappeared because it was partially defective. If the very high signal intensity region was the bursa, the cartilage cap might already have disappeared or become very thin. Dahlin pointed out that an osteochondroma that has stopped growing has practically no cartilage in the cap.22 In our case, it was unknown whether the cartilage cap of the osteochondroma had already prematurely ossified. It is reported that most patients with regressed osteochondroma are less than 12 years old at the time of diagnosis5; therefore, if the cartilage cap is not detected by MRI, tumor growth might have ceased, and subsequently tumor regression might have occurred by the time of skeletal maturation.
Conclusion We present a case of spontaneous regression of solitary osteochondroma. T2-weighted MRI imaging demonstrated a very high signal intensity region on the tumor surface that was continuous with the growth plate and partially defective. The region was thought to be the cartilage cap or bursa, and the cartilage cap might already have disappeared or become very thin. If the
671
cartilage cap was not detected on follow-up MRI, tumor growth might have ceased, and the osteochondroma might have regressed by the time of skeletal maturation.
References 1. Fletcher CDM, Unni KK, Merteus F. WHO classification of tumors of soft tissue and bone. Lyon: IARC Press; 2002. 2. Harsha WN. The natural history of osteocartilaginous exostosis (osteochondroma). Am Surg 1954;20:65–72. 3. Jaffe HL. Tumors and tumorous conditions of the bones and joints. Philadelphia: Lea & Febiger; 1958. p. 143–67. 4. Campanacci M. Bone and soft tissue tumors. 2nd edn. Wien New York and Piccin Padova: Springer-Verlag; 1999. 5. Arkader A, Dormans JP, Gaugler R, Davidson RS. Spontaneous regression of solitary osteochondroma: reconsidering our approach. Clin Orthop 2007;460:253–7. 6. Yasuda H, Ieguchi M, Hoshi M, Taguchi S, Aono K, Takaoka K. Spontaneous regression of exostosis of tibia: a case report. Cent Jpn J Orthop Traumatol 2008;51;67–8 (in Japanese). 7. Choi JY, Hong SH, Kim HS, Chang CB, Lee YJ, Kang HS. Resorption of osteochondroma by accompanying pseudoaneurysm. AJR Am J Roentgenol 2005;185:394–6. 8. Hoshi M, Takami M, Hashimoto R, Okamoto T, Yanagida I, Matsumura A, et al. Spontaneous regression of osteochondromas. Skeletal Radiol 2007;36:531–4. 9. Copeland RL, Meehan PL, Morrissy RT. Spontaneous regression of osteochondromas: two case reports. J Bone Joint Surg Am 1985;67:971–3. 10. Castriota-Scanderbeg A, Bonetti MG, Cammisa M, Dallapiccola B. Spontaneous regression of exostoses: two case reports. Radiology 1995;25:544–8. 11. Paling MR. The “disappearing” osteochondroma. Skeletal Radiol 1983;10:40–2. 12. Sellink JL. Spontaneous regression of an exostosis. J Belge Radiol 1960;43:177–9. 13. Callan JE, Wood VE, Linda L. Spontaneous resolution of an osteochondroma. J Bone Joint Surg Am 1975;57:723–5. 14. Merle P, Rougier JL, Duclos AM, Gras JC. Evanescent exostosis: a report on one case. J Radiol 1980;61:291–2 (author’s translation). 15. Montgomery DM, LaMont RL. Resolving,solitary osteochondromas: a report of two cases and literature review. Orthopedics 1989;12:861–3. 16. Claikens B, Brys P, Samson I, Baert AL. Spontaneous resolution of a solitary osteochondroma. Skeletal Radiol 1998;27:53–5. 17. Revilla Y, Lozano MC, González G, Martínez A. Evanescent exostosis: a new case. Eur J Radiol 1999;29:270–2. 18. Yamamoto T, Kurosaka M, Mizuno K. Spontaneous resolution of a phalangeal solitary osteochondroma. J Hand Surg [Am] 2001;26:556–8. 19. Yanagawa T, Watanabe H, Shinozaki T, Ahmed AR, Shirakura K, Takagishi K. The natural history of disappearing bone tumours and tumour-like conditions. Clin Radiol 2001;56:877–86. 20. Reston SC, Savva N, Richards RH. Spontaneous resolution of solitary osteochondroma in the young adult. Skeletal Radiol 2004;33:303–5. 21. Hunter J. The works of John Hunter, with notes by JF Palmar. London: Longmans; 1835. p. 533–4. 22. Dahlin DC. Bone Tumors: general aspects and data on 6221 cases. 3rd edn. Springfield, IL: Charles C Thomas; 1978. p. 18–27.