Yong-Koo Kang

Catholic University of Korea, Sŏul, Seoul, South Korea

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Publications (18)28.18 Total impact

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    ABSTRACT: Elderly patients with osteosarcoma (OSA) are no longer uncommon; however, many questions remain regarding this population. We investigated the clinicopathological characteristics and prognostic factors of OSA in an Asian population over the age of 40 years. This was a multi-national, multi-institutional study by the Eastern Asian Musculoskeletal Oncology Group (EAMOG). A total of 232 patients were enrolled (116 males and 116 females), with a median age of 50 years at diagnosis; 25 (10.8 %) patients exhibited initial metastasis. Median follow-up was 52 months for survivors. We observed 102 osteolytic and mixed radiographic findings for 173 lesions. Histological subtypes other than osteoblastic type were frequent. Radiation-associated OSA was seen in seven patients, with a 5-year overall survival (OS) of 16.7 %. No Paget's OSA was observed. High-grade spinopelvic OSA was seen in 29 (12.5 %) patients. The 5-year OS was 59.4 % in patients without initial metastasis and 45.2 % in patients with spinopelvic OSA. While surgery and initial metastasis were common prognostic factors for OS, chemotherapy was not. Histologic response to neoadjuvant chemotherapy was poor in 61 of 83 patients. This study revealed distinct clinicopathological features of OSA patients over 40 years of age compared with younger patients, such as the high incidence of axial tumors, common osteolytic and mixed radiographic findings, the high frequency of unusual histologic subtypes, and poor prognosis. Contrary to Western elderly patients with OSA, there was no Paget's OSA in this study, which may result in a lower incidence of secondary OSA. Prognostic factor analyses demonstrated chemotherapy did not influence OS.
    Annals of Surgical Oncology 02/2015; DOI:10.1245/s10434-015-4414-6 · 3.94 Impact Factor
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    ABSTRACT: Various diagnostic imaging modalities have been used to evaluate the effect of neoadjuvant chemotherapy for osteosarcoma early and noninvasively. We evaluated the effectiveness of imaging studies of plain radiographs and positron-emission tomography/computed tomography (PET/CT) in predicting neoadjuvant chemotherapy effect for osteosarcoma and tried to establish a general principle in interpretation of PET/CT parameters.
    01/2014; 20(2):66. DOI:10.5292/jkbjts.2014.20.2.66
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    ABSTRACT: Synovial chondromatosis (SC) is a benign proliferative process of synovial tissue creating multiple cartilaginous nodules in joints. It most commonly occurs in the large joints of the knee, hip, and shoulder, uncommonly in the small joints of the hand and foot, and only rarely in the tenosynovial membrane of tendon sheath, termed tenosynovial chondromatosis (TC). Unlike SC, TC predisposes to the foot or hand. The rarity and unfamiliarity of imagers with TC, as well as the variability of its histologic features often lead to an erroneous diagnosis of extraskeletal chondroma or even chondrosarcoma as in the present case. Calcium pyrophosphate dehydrate (CPPD) crystals are usually deposited in the articular cartilage or periarticular structures such as synovium and capsule, and rarely in other soft tissue structures including bursa, tendon, subcutaneous tissue, and dura mater. CPPD crystals may also be deposited in extraskeletal chondroma and SC. We present an exceptionally rare case of huge tophaceous pseudogout associated with TC that is considered to arise from the flexor digitorum longus tendon sheaths of the foot, initially mistaken for a chondrosarcoma.
    Skeletal Radiology 07/2013; 42(12). DOI:10.1007/s00256-013-1672-x · 1.74 Impact Factor
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    ABSTRACT: Skeletal metastasis is a common event during the advanced stage of a malignant tumour, but metastasis to the hand is rare (about 0.1% incidence). We have seen seven cases of metastatic malignant tumour of the hand since 1983, and report them here.
    04/2011; 45(2):90-5. DOI:10.3109/2000656X.2011.556224
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    ABSTRACT: Giant-cell tumor (GCT) of bone is a common primary benign tumor with high local recurrence and potential distant metastasis or malignant transformation. We have investigated the clinical behavior of recurrent GCT of bone in the extremities. We retrospectively reviewed 110 patients with recurrent GCTs of bone in the extremities treated by the Eastern Asian Musculoskeletal Oncology Group. The factors that affected the number of recurrences and distant metastasis were analyzed. The median interval between initial surgery and the first recurrence of GCT was 16 months (2-180 months). All patients received additional surgery for first recurrence. Twenty-five patients had a second recurrence and 6 patients had a third recurrence. The mean interval between the initial surgery and the first recurrence correlated with the eventual number of recurrences-14.1 months for the repeated recurrence groups (two and three recurrences) and 28.3 months for the single recurrence group (p = 0.016). Campanacci grade did not correlate with repeated recurrence (p = 0. 446). The venue of the initial surgery did not correlate with recurrence but did affect preservation of the adjacent joint (chi-squared test; p = 0.046). Campanacci grade II and III also correlated with sacrifice of the adjacent joint (p = 0.020). The incidence of lung metastasis and malignant transformation were 7.5% (8 out of 107 patients) and 2.7% (3 out of 110 patients), respectively. Repeat recurrence was associated with lung metastasis (p = 0.018). Early local recurrence of GCT is a risk factor for repeat recurrence. Repeat recurrence also correlates with lung metastasis. Recurettage with meticulous adjuvant treatment to completely preclude recurrent lesions is a reasonable method for preserving the adjacent joint. However, a continuous careful follow-up is mandatory.
    Journal of Orthopaedic Science 02/2011; 16(2):196-202. DOI:10.1007/s00776-011-0030-x · 1.01 Impact Factor
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    ABSTRACT: This study was aimed to evaluate the result of inlay cortical strut bone grafts for large cysts or cavitary bone lesions in long bones.
    01/2011; 17(2):73. DOI:10.5292/jkbjts.2011.17.2.73
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    Acta oncologica (Stockholm, Sweden) 08/2010; 49(6):868-72. DOI:10.3109/02841861003739348 · 3.71 Impact Factor
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    ABSTRACT: Kimura's disease is a rare, benign lymphoproliferative disorder of unknown etiology. It occurs most often in Asian men, usually in the second or third decade of life. Most lesions occur in the head and neck followed by the axilla, groin, popliteal region, and arm. The lesions are commonly found in soft tissues. To the best of our knowledge, there has been only one case report of bone involvement in Kimura's disease presented on plain radiography. We report a case of Kimura's disease that involved the proximal meta-diaphysis of the humerus and adjacent soft tissue shown on radiography and MR imaging.
    Skeletal Radiology 05/2010; 39(5):495-500. DOI:10.1007/s00256-009-0863-y · 1.74 Impact Factor
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    ABSTRACT: To analyze clinical, radiological and pathological features as well as clinical outcome after surgical treatment of patients with secondary chondrosarcoma arising from osteochondroma(tosis).
    01/2010; 16(1). DOI:10.5292/jkbjts.2010.16.1.21
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    01/2010; 16(1). DOI:10.5292/jkbjts.2010.16.1.14
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    ABSTRACT: The objectives of this communication were to discuss radiographic and magnetic resonance (MR) imaging manifestations and clinical outcome after complete and incomplete resection of the mass of dysplasia epiphysealis hemimelica (DEH). Clinical records, radiographs, and MR images of eight patients with DEH were retrospectively examined. Six patients were treated by complete excision of the lesional mass, and two patients were treated by incomplete resection at our University Hospitals during the period from 1980 to 2006. We found that, unlike in osteochondroma, DEH was radiographically not clearly separable from the underlying or host bone with preserved cortical bone and marrow continuity. The finding in the talus distinguished DEH from (osteochondroma-like) parosteal osteosarcoma, in which a radiolucent demarcation line clearly separated the tumor from the host bone. The DEH mass had a well-defined low to intermediate signal intensity on T1-weighted images and an intermediate to high signal intensity on T2-weighted images, with irregularity of the articular surface. Simple excision was performed in all patients. The excision was complete in six patients and incomplete in two patients whose lesions was juxta-articular in the ankle and articular in the knee, respectively. The residual mass slowly absorbed and vanished, resulting in mild flaring of the affected portion of the epiphysis. No local recurrence or complication was seen in any of the eight patients. Although the radiographic signs of DEH are characteristic, (osteochondroma-like) parosteal osteosarcoma should be differentiated from DEH when there is a radiolucent separation line between the mass and host bone in the talus. Simple excision was effective in the management of DEH if the deformity was not complicated. Incompletely excised masses resolved and vanished with time.
    Skeletal Radiology 10/2009; 39(1):85-90. DOI:10.1007/s00256-009-0803-x · 1.74 Impact Factor
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    ABSTRACT: OBJECTIVE: Enchondroma protuberans is a rare tumor that arises from an intramedullary enchondroma with an exophytic growth pattern. The purpose of this study was to describe imaging findings of this disease that were obtained using both radiography and MRI. CONCLUSION: It is necessary to understand the characteristic imaging findings of enchondroma protuberans to avoid misdiagnosis. When radiography does not allow a clear diagnosis of enchondroma protuberans, MRI may be helpful for diagnosis.
    American Journal of Roentgenology 02/2008; 190(1):40-4. DOI:10.2214/AJR.07.2529 · 2.74 Impact Factor
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    ABSTRACT: Prominent osteolysis associated with "ground glass" density of fibrous dysplasia may indicate cystic change or sarcomatous transformation. This complication has been reported only sporadically in the long bones. This article presents clinical, radiographic, and pathologic findings, and outcome of simple curettage and bone graft observed in a series of 8 patients with prominent cystic fibrous dysplasia of the long bone. Magnetic resonance imaging features provide a basis for separation of benign cystic change from malignant transformation. However, biopsy is necessary to distinguish nonspecific cystic degeneration from secondary aneurysmal bone cyst. Simple curettage with allo-chip-bone graft is an effective treatment for cystic fibrous dysplasia.
    Orthopedics 11/2007; 30(10):871-3. · 0.98 Impact Factor
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    ABSTRACT: Metastatic malignant tumor of the hand is unusual and the most common site of the primary cancer is lung. Acrometastases to the phalanges of the hand usually involve a single bone, while those proximal to the phalanges often involve multiple bones. Metastasis to the hand from gastrointestinal cancer, particularly from gastric cancer, is extremely rare. To our knowledge, only five cases have been reported in the literature to date and there has been no reported case following closed intramedullary nailing for metastatic diaphyseal fracture of an ipsilateral long bone. We present a very unusual case of gastric cancer, which metastasized to all fingertips of the ipsilateral hand after closed interlocking intramedullary nailing of a pathologic fracture of the humerus.
    Skeletal Radiology 08/2006; 35(7):529-32. DOI:10.1007/s00256-005-0047-3 · 1.74 Impact Factor
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    ABSTRACT: The purpose of our study was to evaluate whether MRI can discriminate between extraaxial neurofibromas and neurilemmomas. MR images of 52 patients with a pathologically proven extraaxial neurofibroma or neurilemmoma were retrospectively reviewed by observers who were unaware of the surgical results, regarding the presence or absence of individual imaging criteria. MRI findings in 12 patients with a localized neurofibroma and 40 patients with a neurilemmoma were compared using the chi-square test or Fisher's exact test. MRI findings suggestive of neurofibroma (p < 0.05) were a target sign on T2-weighted images (58% in neurofibromas vs 15% in neurilemmomas), central enhancement (75% vs 8%), and a combination of both findings (63% vs 3%). MRI findings suggestive of a neurilemmoma (p < 0.05) were a fascicular appearance on T2-weighted images (25% vs 63%), a thin hyperintense rim on T2-weighted images (8% vs 58%), a combination of both findings (8% vs 48%), and diffuse enhancement (13% vs 67%). No significant difference was seen between neurofibromas and neurilemmomas for a centrally entering and exiting nerve (42% in neurofibromas vs 23% in neurilemmomas), a peripherally entering and exiting nerve (58% vs 77%), a cystic area (38% vs 64%), a low-signal margin (100% vs 100%), peripheral enhancement (13% vs 26%), or a target sign on contrast-enhanced images (11% vs 31%). MRI shows features helpful for differentiating extraaxial neurofibromas from neurilemmomas; however, no single finding or combination of findings allows definitive differentiation.
    American Journal of Roentgenology 09/2004; 183(3):629-33. DOI:10.2214/ajr.183.3.1830629 · 2.74 Impact Factor
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    ABSTRACT: The aim of this study was to evaluate MR imaging findings of the associated findings in surrounding tissues of the extra-articular soft tissue ganglion cysts around the knee. We retrospectively reviewed MR images of 30 patients who had surgically confirmed extra-articular soft tissue ganglion cysts around the knee with focus on the associated findings in surrounding tissues, such as muscle, subcutaneous fat, bone, and nerve. The most common associated finding was the visualization of channel between ganglion cyst and the joint, which was demonstrated in 20 cases (continuous type in 12 cases and discontinuous type in 8 cases). Other associated findings were seen in 15 cases; pericystic edema ( n=9), bony remodelling ( n=3), and nerve involvement ( n=3). The bony remodelling involved the proximal metaphysis of tibia in all 3 cases. Two patients with nerve involvement had deep peroneal nerve in subacute phase and one involved common peroneal nerve in chronic phase. The MR imaging is a useful imaging modality to evaluate the associated findings in extra-articular soft tissue ganglion cysts around the knee. The evaluation of these associated findings is helpful for the differentiation of ganglion cysts from other cystic lesions around the knee.
    European Radiology 02/2004; 14(1):106-11. DOI:10.1007/s00330-003-1969-6 · 4.34 Impact Factor
  • Won-Jong Bahk · Yong-Koo Kang · An-Hee Lee · Joseph M Mirra
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    ABSTRACT: Desmoid tumor of bone, also termed desmoplastic fibroma or aggressive fibromatosis, is a rare, locally aggressive fibroblastic tumor. We present a 16-year-old male with a huge desmoid tumor involving the iliac wing. It was associated with enchondromatous nodules mimicking malignancy. The tumor in this patient was mistaken for chondrosarcoma and hemipelvectomy was performed. To our knowledge, such a case has not previously been documented fully in the English literature. The radiographic and pathologic findings and a possible mechanism of enchondromatous nodule formation in fibrous bone tumors are discussed.
    Skeletal Radiology 05/2003; 32(4):223-6. DOI:10.1007/s00256-002-0570-4 · 1.74 Impact Factor