Comparison of epoprostenol and viscum album efficiencies in the treatment of avascular necrosis of the femoral head: An experimental animal study.

BACKGROUND: The aim of our study is to compare the efficacy of epoprostenol and viscum album in the treatment of femoral head avascular necrosis with an experimental study. Our hypothesis is that viscum album, which has similar properties to epoprostenol on the vascular system, is as effective as epoprostenol in the treatment of avascular necrosis. METHODS: Avascular necrosis was created on the femoral heads of 45 New Zealand type rabbits by surgical vascular deprivation method. The rabbits were divided into 3 groups. Group 1 was designed as a control group, in group 2 Ilomedin (epoprostenol analogue) was administrated to subjects and in group 3, Helixor (viscum album extract) was administrated. At the end of the study, there were nine subjects in each group. Osteocyte necrosis, bone marrow necrosis, new bone formation and cartilage degeneration were evaluated microscopically. The extent of bone necrosis and repair and involvement of epiphysis, the bone marrow cellularity ratio and trabecular bone volume were investigated. RESULTS: Subchondral necrosis was seen in more animals in the control group (p=0.03). Osteoblastic and osteoclastic activity were more prominent in the Ilomedin group (p=0.25 and 0.07, respectively). It was seen that the cartilages of the subjects in the Helixor and Ilomedin groups were less damaged. In the Ilomedin group, more animals were seen in the chronic phase of the repair process than in the other groups (p=0.07). Bone marrow cellularity was higher in treatment groups (22% and 20,6% for Ilomedin and Helixor, respectively, p=0,04). Trabecular volume was found to be increased in damaged femoral heads in the treatment groups, the highest increased observed in the Helixor group (p=0.01). CONCLUSION: Viscum album seems to be effective in decreasing the extention of necrosis and protecting the articular cartilage, and epoprostenol in increasing repair and regeneration.

Melatonin in preservation solutions prevents ischemic injury in rat kidneys.

Transplantation is lifesaving and the most effective treatment for end-stage organ failure. The transplantation success depends on the functional preservation of organs prior to transplantation. Currently, the University of Wisconsin (UW) and histidine-tryptophan-ketoglutarate (HTK) are the most commonly used preservation solutions. Despite intensive efforts, the functional preservation of solid organs prior to transplantation is limited to hours. In this study, we modified the UW solution containing components from both the UW and HTK solutions and analyzed their tissue-protective effect against ischemic injury. The composition of the UW solution was changed by reducing hydroxyethyl starch concentration and adding Histidine/Histidine-HCl which is the main component of HTK solution. Additionally, the preservation solutions were supplemented with melatonin and glucosamine. The protective effects of the preservation solutions were assessed by biochemical and microscopical analysis at 2, 10, 24, and 72 h after preserving the rat kidneys with static cold storage. Lactate dehydrogenase (LDH) activity in preservation solutions was measured at 2, 10, 24, and 72. It was not detectable at 2 h of preservation in all groups and 10 h of preservation in modified UW+melatonin (mUW-m) and modified UW+glucosamine (mUW-g) groups. At the 72nd hour, the lowest LDH activity (0.91 IU/g (0.63-1.17)) was measured in the mUW-m group. In comparison to the UW group, histopathological damage score was low in modified UW (mUW), mUW-m, and mUW-g groups at 10, 24, and 72 hours. The mUW-m solution at low temperature was an effective and suitable solution to protect renal tissue for up to 72 h.

The effect of N-acetyl cysteine on biofilm layers in an experimental model of chronic otitis media.

OBJECTIVE: The aim of this study was to investigate the efficacy of N-acetylcysteine (NAC) on biofilm layers and on the course of disease in chronic otitis media. METHODS: Twenty-five rats that were induced with chronic otitis media (COM) were separated into three groups. In Group 1 (N = 18), 0.2% ciprofloxacin + 0.1% dexamethasone sodium phosphate + 0.5 mg/ml NAC solution was locally injected to the right ear of the rats; in Group 2, (N=18) 0.2% ciprofloxacin + 0.1% dexamethasone sodium phosphate was locally injected to the left ear of the rats. No treatment was applied to either ear of rats in Group 3 (N = 5). Histopathological and scanning electron microscope (SEM) evaluations were performed in all groups. RESULTS: SEM revealed biofilm formation in all COM induced groups. No significant difference was seen between groups 1 and 2 in terms of suppuration levels, fibrosis, inner ear involvement, infection staging and biofilm formation (p > 0.05). CONCLUSIONS: In this study, while histopathological and SEM evaluation revealed no effect of 0.5 mg/ml NAC on the biofilm layer in COM-induced rats, further studies with NAC at different concentrations are still needed on different types of experimental animals.

Effects of Three Different Frequencies of Aerobic Physical Activity on Heart and Kidney Tissues in Type 2 Diabetes-Induced Rats.

OBJECTIVE: Exercise has many beneficial effects in the treatment and prevention of Type 2 Diabetes Mellitus (T2DM). The aim of this study was to evaluate the effect of physical activities with different frequencies performed within a total total duration of one week on the heart and kidney tissues and vascular endothelial growth factor (VEGF) expressions in experimental T2DM model. METHOD: Rats (n: 30) were divided into sedentary control (SC), sedentary T2DM (SD), T2DM and continuous exercise (DEc, 30 min/day, 5 days/week), T2DM and short bouts exercise (DEsb, 3x10 min/day, 5 days/week), T2DM and weekend warrior exercise (DEww, 35+40 min/day, 2 days/week) groups. Rats were administered streptozotocin (65 mg/kg) and nicotinamide (110 mg/kg) through intraperitoneal route. After 6-weeks of swimming exercise (total duration 150 min/week), biochemical analyzes were performed to measure oral glucose tolerance test, insulin sensitivity and cytokines. Histopathological and immunohistochemical analyses [VEGF, capillary density, Transforming growth factor beta (TGF-ß)] were performed in heart and kidney tissues. RESULTS: Compared with sedentary T2DM rats, significant improvements were observed in all exercise groups in terms of blood glucose level, insulin sensitivity, capillary density in heart tissue, VEGF expressions in tissues, TGF-ß expressions in kidney tissue and all histopathological analysis (p<0.05). CONCLUSION: This study shows that physical activity at various frequencies may significantly ameliorate harmful effects of T2DM on heart and kidney tissue without significant differences between exercise frequencies, provided that the total duration of aerobic exercise remains the same (150 min/week).

Effect of adjuvant hyperbaric oxygen on healing of cartilage lesions treated with microfracture: an experimental study in rats.

PURPOSE: The purpose of this experimental study was to investigate the effect of hyperbaric oxygen (HBO2) therapy combined with microfracture technique in the treatment of cartilage lesions. METHODS: Adult Wistar rats (n=44) were divided into six groups. In Groups A, B, C and D, ICRS* (* International Cartilage Repair Society) grade 4 cartilage lesions were made on the femoral sulcus of both knees. Lesions were microfractured on the left knees; the right knees had no further procedure. Groups E and F had no surgery. Groups A, C and E received HBO2 therapy once a day, six days a week postoperatively. Groups B, D and F had no HBO2 therapy. The animals in Groups A, B, E and F were sacrificed after two weeks; Groups C and D were sacrificed after four weeks. Semiquantitative scale - including filling of defect (microfracture hole), reparative tissue thickness, cell morphology and subchondral bone maturation - was used for evaluation. The Mann-Whitney test was used to compare individual and total scores. RESULTS: Total scores of the two-week group with adjuvant HBO2 therapy were significantly higher (P=0.0007) than the two-week standard treatment group. Except for subchondral bone maturation, individual scores were significantly higher in the two-week group with adjuvant HBO2 therapy. Total scores of the four-week groups were similar. Among individual scores of the four-week groups, filling of the defect (microfracture hole), and subchondral bone maturation were significantly higher (P=0.01, P=0.03) in groups with adjuvant HBO2 therapy. CONCLUSIONS: Adjuvant HBO2 therapy accelerates the healing process of cartilage lesions treated with microfracture in rats.

Actinomycosis osteomyelitis of the jaws: Report of four cases and a review of the literature.

Actinomycosis osteomyelitis of the jaw bones, particularly in the maxilla, is an extremely rare disease. This report presents two cases of maxillary and two cases of mandibular actinomycosis osteomyelitis, with the diagnosis particularly based on histological procedures. The highly diversified pathogenicity of the phenomenon and the absence of solid diagnostic criteria are discussed. Laboratory challenges are emphasized, and a comprehensive overview of the entity including treatment alternatives is given along with a review of the relevant literature.

Cystic bone lesions: histopathological spectrum and diagnostic challenges.

OBJECTIVE: Bone cysts are benign lesions occurring in any bone, regardless of age. They are often asymptomatic but may cause pain, swelling, fractures, and local recurrence and may be confused with other bone lesions. MATERIAL AND METHOD: We retrospectively re-evaluated 143 patients diagnosed with aneurysmal bone cyst (n=98, 68.5%), solitary bone cysts (n=17 11.9%), pseudocyst (n=10.7%), intraosseous ganglion (n=3, 2.1%), hydatid cyst (n=2; 1.4), epidermoid cyst (n=1, 0.7%) and cysts demonstrating "mixed" aneurysmal-solitary bone cyst histology (n=12, 8.4%), and compared them with nonparametric tests. RESULTS: Aneurysmal bone cyst, solitary bone cysts and mixed cysts were frequently seen in the first two decades of life while the others occurred after the fourth decade. Aneurysmal bone cysts, intraosseous ganglion and pseudocysts were more common in women contrary to solitary bone cyst and mixed cysts (the female/male ratio was 1.22, 2 and 1.5 versus 0.7 and 0.5, respectively). Aneurysmal bone cyst, solitary bone cysts and "mixed" cysts were mostly seen in long bones, predominantly the femur, while epidermoid, hydatid and pseudocysts were all seen in flat bones like the vertebra, pelvis and mandible (p=0.001, chi-square). Repeat biopsies were performed in 19 cases (13.3%), 84.2% of which were aneurysmal bone cyst (5 conventional, 9 solid, 1 secondary and 1 subperiosteal) and three (15.8%) were mixed cysts (p=0.02, chi-square). Notably, some of them were located in inaccessible areas of pelvis (n=3), femur (n=3) and maxilla (n=2). CONCLUSION: The most common and challenging intraosseous cysts are aneurysmal bone cysts, particularly the "solid" variant. The "mixed" aneurysmal-solitary bone cyst "subgroup" requires further research with larger series to be defined more thoroughly.

Clinical and morphological characteristics of osteoid osteoma and osteoblastoma: a retrospective single-center analysis of 204 patients.

Osteoid osteoma and osteoblastoma are histologically similar, benign bone-forming tumors. In this retrospective study, we aimed to evaluate the natural history; clinical, pathologic, and radiologic findings; and treatment results in 204 patients between 1959 and 2006 in a single institution. According to the World Health Organization's definition, tumors ≤1 cm in diameter were classified as osteoid osteoma, and those ≥2 cm, as osteoblastoma. For tumors between 1 cm and 2 cm, other criteria, such as the bone involved, the site, the presence of a nidus, and presence of peripheral sclerosis, were used for diagnosis. There were 131 patients with osteoid osteoma (93 male, 38 female) and 73 patients with osteoblastoma (40 male, 33 female). The mean age in the osteoid osteoma and osteoblastoma groups was 16.4 ± 7 and 19.6 ± 9.9 years, respectively. The osteoid osteoma cases were mostly localized in the extremities, whereas the osteoblastoma cases involved the vertebral column and sacrum. The nidus size varied between 0.2 and 1.5 cm in osteoid osteoma cases, and the tumor size range was 1.3-10 cm in the osteoblastoma cases. The pain was encountered in 89% of osteoid osteoma and 45% of osteoblastoma patients. Histopathology was similar in both cases. The treatment of choice was conservative surgery for both diagnoses. In conclusion, osteoblastoma is clinically and radiologically more aggressive than osteoid osteoma.

Autopsy findings of a case with oxalosis.

Oxalosis, deposition of calcium oxalate in tissues, is the final stage of hyperoxaluric syndromes. Being a rare entity, it is often missed, or the diagnosis is delayed, since the definitive diagnosis requires special laboratory tests. Kidneys, the walls of blood vessels, and bones are the major sites for crystal deposition. We report the autopsy findings of a 4-year-old girl who presented with end-stage renal disease in which the clinical presentation was consistent with primary hyperoxaluria Type I. The case is unusual, as there was extensive crystal deposition throughout the body, including in tissues that are rarely involved, such as ovaries, fallopian tubes, uterus, thymus, salivary glands, pancreas, and bladder.

Paraganglioma of the thoracic spine.

A 49-year-old man was admitted to hospital for treatment of a T10-11 paraspinal lesion, which was detected incidentally. He had suffered from facial flushing and palpitations associated with hypertension for many years. MRI confirmed the presence of a large, well-demarcated tumour in the left paraspinal area of the T10-11 vertebral bodies. Grossly complete excision was achieved without neurological complications. Post-operatively, the patient was normotensive with no adrenergic symptoms.

Comparison of the effects of Artemisia vulgaris and Artemisia absinthium growing in western Anatolia against trichinellosis (Trichinella spiralis) in rats.

Trichinellosis often causing diarrhea and more rarely fever, periorbital edema and myositis in human, is commonly treated with benzimidazole derivatives. The Artemisia genus has been found to be effective against a variety of parasites. In the present study, the efficacy against trichinellosis (Trichinella spiralis) of Artemisia vulgaris and Artemisia absinthium was examined for the first time in rats. The results of trichinoscopy and artificial digestion, during the enteral (adult) phase of the illness show that 300 mg/kg doses of methanol extracts of the aerial parts of A. vulgaris and A. absinthium reduced the larval rate by 75.6% and 63.5% in tongue, 53.4% and 37.7% in diaphragm, 67.8% and 46.2% in quadriceps, and 66.7% and 60.5% in biceps-triceps muscles of rats, respectively. Furthermore, during the parenteral (encapsulated larvae) phase, 600 mg/kg doses of A. vulgaris and A. absinthium extracts decreased the larval rate by 66.4% and 59.9% in tongue, 57.4% and 50.0% in diaphragm, 47.6% and 43.7% in quadriceps, 60.2% and 46.4% in biceps-triceps muscles of rats, respectively. Analysis of antibody also showed that A. vulgaris significantly reduced the antibody response (P<0.05) during the enteral and parenteral phases. Thus, the results of the present study revealed that A. vulgaris could be an alternative drug against trichinellosis.

Constructive effect of exogenous melatonin against osteoporosis after ovariectomy in rats.

OBJECTIVE: To analyze histomorphometric, densitometric and biochemical effects of melatonin on osteoporosis in ovariectomized rats. STUDY DESIGN: Wistar rats were divided into 6 groups. Group C: control; Group I: bilateral ovariectomy (OVX); Group II: OVX + vehicle; Group III: OVX + 10 mg/kg/day melatonin (MLT); Group IV: OVX + 30 mg/kg/day MLT; Group V: sham + 10 mg/kg/day MLT. Cortex, trabecula, osteoblast and osteoclast numbers were evaluated on vertebra and femur histomorphometrically. Hydroxyproline analysis was used to determine collagen content of femur and vertebrae. Bone mineral density and bone mineral content were measured. RESULTS: Trabecular thickness and trabecular area of vertebra and femur and cortical thickness of femur showed remarkable decrease after OVX, but increased after MLT treatment in the OVX+MLT groups. Following OVX, no statistically significant difference was found in number of osteoblasts or osteoclasts, trabecular number or levels of hydroxyproline after treatment with MLT. OVX caused significant decrease in bone mineral density, but treatment with MLT was unable to reverse this effect. CONCLUSION: MLT may trigger microscopic changes in bone, and time of application is critical for clinical recovery. It can be effective in helping treat postmenopausal osteoporosis. However, it is contraindicated in women who have normal-functioning ovaries.

Erdheim-Chester disease: the effect of bisphosphonate treatment--a case report.

Erdheim-Chester disease is a distinctive pathologic and radiographic entity characterized by bilateral symmetric sclerosis of the diametaphyseal regions of long bones and infiltration of foamy lipid-laden histiocytes. It is a rare histiocytic disease of unknown etiology that is characterized pathologically by xanthogranulomatous infiltrates of multiple organs. We present a patient in her early sixties with bilateral mild knee and leg pain. The patient showed a typical bilateral symmetric medullary sclerosis at the diametaphyseal portions of long bones of the lower extremity. The diagnosis was confirmed by a bone biopsy, and bisphosphonate (alendronate, 70 mg/wk) was given to the patient. After 9 months of treatment, biochemical markers of bone turnover, which were high at baseline, decreased to normal ranges. However, the radiographs showed that bone lesions had changed to lytic lesions. We propose use of bisphosphonates, such as alendronate, to decrease the biochemical markers of bone turnover. But we suggest that it is premature to conclude that bisphosphonates have any effect on lytic lesions and the progression of the disease as shown by changes in radiographs. Further studies with long-term follow-up and ultrastructural evaluation are needed.

Solitary eosinophilic granuloma of the third metacarpal at pediatric age.

Langerhans cell histiocytosis involves disorders previously referred to as "histiocytosis X" (including eosinophilic granuloma of bone, Letterer-Siwe, and Hand-Schüller-Christian syndrome). Eosinophilic granuloma of the hand, especially if solitary, is extremely rare. This is the third pediatric case reported in the literature with solitary eosinophilic granuloma of the hand and the second with metacarpal involvement. The patient's lesion was curetted and the histologic examination showed eosinophilic granuloma. The patient received adjuvant radiotherapy because of continuing mild functional impairment and fracture risk. At 12-month follow-up near complete recovery of the lesion was observed. Radiologically, there was sclerosis and remodeling of the third metacarpal. The patient is disease-free at 26 months.

99mTc-MIBI imaging as a predictor of therapy response in osteosarcoma compared with multidrug resistance-associated protein and P-glycoprotein expression.

UNLABELLED: In vitro studies have demonstrated that (99m)Tc-methoxyisobutylisonitrile ((99m)Tc-MIBI) is a transport substrate of multidrug resistance (MDR)-related proteins. The aim of this clinical study was to evaluate whether (99m)Tc-MIBI scintigraphy was a functional imaging tool for in vivo detection of multidrug resistance-associated protein (MRP) expression in osteosarcoma and to investigate the role of MRP and (99m)Tc-MIBI imaging to predict the clinical outcome. We also examined whether the scintigraphic parameters would help to distinguish the functional capacity of P-glycoprotein (Pgp) and MRP. METHODS: Twenty-four patients with a diagnosis of osteosarcoma were studied before neoadjuvant chemotherapy. Tumor-to-background ratios of both early (10 min) and delayed (1 h) images and the percentage washout rate (WR%) of (99m)Tc-MIBI were calculated. Immunohistochemical analysis of MRP and Pgp was performed on biopsy specimens, and the response to preoperative chemotherapy was assessed by histopathologic examination. RESULTS: Fifteen of 24 osteosarcoma samples in our series (62.5%) showed significant expression of MRP. The level of MRP expression was significantly correlated with the WR% of (99m)Tc-MIBI (r = 0.58, P = 0.003), and the WR% of (99m)Tc-MIBI was significantly faster in patients with high MRP expression than in those with a low MRP score (P = 0.007). The clearance rate of (99m)Tc-MIBI was significantly slower in tumor samples with negative or low expression of both Pgp and MRP (16% +/- 6.2%) when compared with osteosarcomas with high expression of both proteins (31.7% +/- 8.7%) (P = 0.001). There was not a significant difference between the WR% of (99m)Tc-MIBI in tumors with coexpression of both proteins and in tumors with high expression of either Pgp or MRP. Both the rate of MRP expression and the WR% of (99m)Tc-MIBI were significantly correlated with response rate. CONCLUSION: Our results suggest that the WR% of (99m)Tc-MIBI is correlated with MRP expression. Both the WR% of (99m)Tc-MIBI and MRP expression are correlated with therapy response. (99m)Tc-MIBI can be used as a general probe for functional imaging of both Pgp and MRP; however, it is not capable of differentiating the functional status of either MDR-related glycoprotein.

Diagnosis of renal amyloidosis using Congo red fluorescence.

Early diagnosis and classification of amyloid deposition and differentiation from other glomerular fibrillar deposits relies on routine Congo red (CR) histochemistry. Congo red fluorescence (CRF) is an alternative method based on examination of the CR-stained section by ultraviolet (UV) light. The aim of this study is to investigate the usefulness of CRF, especially when applied to frozen kidney sections. Congo red fluorescence was applied to sections of frozen kidney biopsies prospectively and to paraffin sections retrospectively. The findings of CRF were compared to CR staining in bright light. Prospectively, 15 cases of amyloidosis were diagnosed on frozen sections and identical CR staining was found in all of the paraffin-stained sections. There were no false positives or negatives. Retrospectively, 146 renal biopsies previously stained with CR were re-evaluated with CRF. Eighty-seven CR positive cases were confirmed by CRF, and one new case was identified. Congo red fluorescence is simple to perform and more pronounced, therefore easier to evaluate than CR in bright light. Congo red, when combined with immunohistochemistry, is still visible under UV whereas CR is masked in bright light. Although not widely used, the CRF method for detecting amyloid is simple to use with a high specificity and sensitivity, and may be applied successfully to frozen sections.

Osteoid osteomas and osteoblastomas of the spine.

OBJECT: Osteoid osteomas and osteoblastomas are rare primary bone tumors that usually do not arise in the spine. In this report the authors analyze 16 cases of osteoid osteoma or osteoblastoma of the spine that were surgically treated over a 27-year period. METHODS: A retrospective study was conducted in which the following data were found: five patients had osteoid osteomas (two male and three female patients) and 11 had osteoblastomas (seven male and four female patients). The site of the tumor was the cervical spine in four, thoracic in six, and lumbar spine in six. In 14 patients, the tumor involved the posterior vertebral elements, with lumbar and thoracic levels being the most common. Only two patients had tumors in the body of a cervical vertebra. The mean age of the patients was 20 years for osteoid osteoma and 19 years for osteoblastoma. The most common symptom was local pain in the area of the tumor. Among 11 patients with osteoblastoma, six (two with paraparesis, four with monoparesis) had neurological deficits caused by extradural compression. None of the patients with osteoid osteoma had neurological deficits. The diameters of osteoblastomas were 3 to 8 cm (mean 4 cm), and those of osteoid osteomas were 1.5 to 2 cm (mean 1.7 cm). Although the peritumoral bone was normal in patients with osteoblastoma, a sclerotic rim was observed in all patients with osteoid osteoma. All patients were treated with resection; tumor excision was complete in 15 cases. Follow-up periods ranged from 2 months to 13 years (mean 36 months). Complete pain relief was achieved in 15 patients; the other patient described mild pain with activity. There was no tumor recurrence except one regrowth in a patient with osteoblastoma who then received radiation therapy. There were two complications: one surgery was performed at the wrong level, and there was one instrument failure that required revision. CONCLUSIONS: With the help of modern imaging modalities that aid in diagnosis and surgical planning, a complete removal and cure may be achieved for most of these rare tumors.

Presentation of a case with Salmonella glomerulonephritis.

Salmonella infection is frequently encountered in childhood, but it is rarely associated with glomerulonephritis. We present in this report a case with Salmonella glomerulonephritis, which is infrequent in children. His general condition was found moderate, and temperature and blood pressure were 38 degrees C and 150/90 mmHg, respectively. The whole blood counts were as follows: white blood cell count 3,800/mm3, hemoglobin 6.3 g/dl and platelet count 240,000/mm3. Serum urea was 140 mg/dl, albumin 2.5 g/dl and complement (C3) 23.6 mg/dl. Both Salmonella type O and Salmonella typhi H were detected positive (1/800 titer). In view of these findings, the case was considered as Salmonella glomerulonephritis; his clinical and laboratory recovery were achieved by supportive therapy.

Treatment results of osteosarcoma of the extremity in children and adolescents at Ege University Hospital.

Twenty-five patients were treated for osteosarcoma of the extremity at Ege University Hospital. Eight of them were metastatic. All patients received cisplatin, doxorubicin, ifosfamide, and methotrexate preoperatively. Twenty-three patients underwent surgery at around week 15 (11-18 weeks). All but one underwent limb-sparing surgery. While good responders continued to receive the same drugs, poor responders were given the same regimen before 1996, but high-dose ifosfamide alone after 1996. For all patients the projected event-free survival (EFS) rates were 63.5% at 2 years and 53% at 5 years. The projected overall survival (OS) rates were 72% at 2 years and 62% at 5 years. For nonmetastatic patients, 5-year EFS and OS rates were 67% as compared with metastatic patients (25 and 50%)(p =. 01 for EFS; p > .05 for OS). The results show that nonmetastatic patients with osteosarcoma of the extremity have favorable prognosis on this therapy regimen, allowing a high rate of limb-sparing surgery.

Clear cell chondrosarcoma: unusual radiologic appearances with histologic correlation.

Clear cell chondrosarcoma is a rare variant of the bone tumors with distinct radiologic and pathologic features. In this report two cases of clear cell chondrosarcomas with atypical radiologic appearances are presented. The findings of X-ray films and MRI are described with histologic correlation. In the first case the lesion showed a very expansile and long segment involvement of the humerus. In the second case the lesion was located in the diaphysis of the femur causing a large cortical destruction.