Osteochondromas are common and typically arise from the metaphyseal ends of long bones. An osteochondral neoplasm of the soft tissue, which is a lesion of uncertain pathogenesis, is uncommon and usually arises from the synovial tissue in joints and tendon sheaths. Rarely, extraskeletal osteochondromas also arise outside of synovial compartments. Most of the reported cases were presented in the hands and feet, especially in the fingers. Here we describe a 44-yr-old female patient who presented with a pain in the left buttock. A well-defined osseous mass was detected in the buttock. It consisted of sharply demarcated, mature hyaline cartilage that was covered with a fibrous capsule, which changed gradually into cancellous bone, more pronouncedly at the center. The diagnosis of an extraskeletal osteochondroma should be considered when a discrete, ossified mass is localized in the soft tissues. A case of pathologically proven extraskeletal osteochondroma of the buttock is presented with a literature review, magnetic resonance imaging, and radiological findings.
Accidental Falls ; Adult ; Buttocks* ; Diagnosis, Differential ; Female ; Human ; Myositis Ossificans/diagnosis ; Osteochondroma/complications ; Osteochondroma/diagnosis* ; Osteochondroma/radiography ; Osteochondroma/surgery ; Pain/etiology ; Sarcoma/diagnosis ; Soft Tissue Neoplasms/complications ; Soft Tissue Neoplasms/diagnosis* ; Soft Tissue Neoplasms/radiography ; Soft Tissue Neoplasms/surgery

A 60-year-old female presented with a slowly growing, painful mass in the superolateral portion of the rightt high. Physical examination, roentgenography, bone scan and magnetic resonance imaging revealed a soft tissue masswith mineralization which did not involve bone or joint. A triangular-shaped, mineralized lesion was found in the superior side of the greater trochanter on simple radiograph and on magnetic resonance imaging. It had not been detected clinically, and was asymptomatic. The masses were removed en bloc and diagnosed as extra articular osteochondroma. Eight months postoperatively, pain had almost been relieved.
Chondromatosis, Synovial* ; Female ; Femur ; Humans ; Joints ; Magnetic Resonance Imaging ; Middle Aged ; Osteochondroma ; Physical Examination ; Radiography

Bone Neoplasms ; diagnostic imaging ; pathology ; secondary ; surgery ; Chondrosarcoma ; diagnostic imaging ; pathology ; secondary ; surgery ; Fingers ; Humans ; Male ; Middle Aged ; Osteochondroma ; pathology ; Radiography

OBJECTIVE: Ultrasonography (USG) of joints has a unique position for the diagnosis of joint diseases. Bone surface, cartilage, periarticular soft tissue and their pathologic changes can be assessed by USG. This study was aimed to compare the radiographic and ultrasonographic findings in osteoarthritis (OA) of the knee joint and to evaluate the usefulness of each modality to evaluate the disease early and determine the severity of the arthritis. METHODS: Fifty osteoarthritis patients classified by the American College of Rheumatology (ACR) clinical criteria from December 2002 to April 2003 were included in the study. Routine radiography (standing anteroposterior, lateral, skyline view) and systemic USG examination of both knee were performed. We compared the incidence of the radiographic and ultrasonographic abnormality related to the pathologic change of the knee OA and suggesting the severity of the OA which would help to decide the therapeutic modality. RESULTS: In patient with knee OA, plain radiography showed abnormal findings in 37/50 (74%) patients, but USG showed at least five abnormal findings in all 50 patients. The abnormal findings detected only by plain radiography were subchondral sclerosis and subchondral cyst (14% and 4% each). But, the thinning of cartilage (94%), Baker's cyst (94%), cartilage degeneration (54%), meniscal protrusion (44%), meniscal tear (34%), meniscal cyst (32%), and the pannus (22%) were detected only by USG. Among the findings shared by both method, joint space narrowing was detected better by plain radiography than USG, but fluid accumulation, spur, meniscal calcification and osteochondroma were detected more frequently by USG. CONCLUSION: USG is more sensitive to find the pathologic changes related to the knee OA and to diagnose OA than the plain radiography. But each of the plain radiography and USG have their own unique value for the evaluation of OA in the knee. So the USG supplements the plain radiography in the examination of the knee OA.
Arthritis ; Bone Cysts ; Cartilage ; Diagnosis ; Humans ; Incidence ; Joint Diseases ; Joints ; Knee Joint ; Knee* ; Osteoarthritis ; Osteoarthritis, Knee* ; Osteochondroma ; Popliteal Cyst ; Radiography* ; Rheumatology ; Sclerosis ; Ultrasonography*

OBJECTIVETo investigate the clinicopathologic, radiological and immunohistochemical characteristics of osteochondroma with malignant transformation.

METHODSThe clinical data, radiological imagings and hematoxylineosin stained histologic sections were reviewed in 463 cases of osteochondroma diagnosed in Shanghai 6th Hospital from 1991 to 2008, including 11 cases with malignant transformation. Immunohistochemical two-step staining was used to detect CK, vimentin, S-100 protein, p53 and c-myc expression in seven cases of osteochondroma with malignant transformation and 10 cases without malignant transformation. The relevant literature was reviewed.

RESULTSAmong the 11 cases with malignant transformation, five were single osteochondroma (5/408, 1.2%), and six were multiple osteochondromas (6/55, 10.9%). The male to female ratio was 10:1. These 11 cases were derived from femur (4 cases), tibia (3 cases), ilium (3 cases), shoulder bone (1 case) and pubis (1 case). There was one case that showed malignant transformation in both the femur and ilium. The mean ages for the malignant and non-malignant cases were 39.8 years and 20.4 years respectively. All the malignant cases showed large sized lesions with prominent calcification in the thick cartilage caps. The malignant component was low grade, peripheral chondrosarcoma (grade I-II). In some areas the tumor cells infiltrated the peripheral soft tissue and bone marrow. Of the seven cases with malignant transformation that had immunohistochemical staining, all were positive for vimentin and S-100 protein; p53 protein was positive in 2 of 7 cases.

CONCLUSIONSMalignant transformation of osteochondroma was usually encountered in multiple lesions. Most patients were more than 30 years old with a long clinical history and with a male predominance. These tumors showed thick cartilage caps with prominent calcification. The lobulated nature of the tumors was evident and they infiltrated the surrounding soft tissue. The sarcomatoid component was peripheral type, well differentiated chondrosarcoma. p53 mutation may explain part of the molecular mechanism in the malignant transformation.

Adult ; Aged ; Bone Neoplasms ; diagnostic imaging ; metabolism ; pathology ; surgery ; Cell Transformation, Neoplastic ; pathology ; Chondrosarcoma ; diagnostic imaging ; metabolism ; pathology ; surgery ; Exostoses, Multiple Hereditary ; diagnostic imaging ; metabolism ; pathology ; surgery ; Female ; Humans ; Male ; Middle Aged ; Osteochondroma ; diagnostic imaging ; metabolism ; pathology ; surgery ; Radiography ; S100 Proteins ; metabolism ; Tumor Suppressor Protein p53 ; metabolism ; Vimentin ; metabolism ; Young Adult