A genetic factor associated with low final bone mineral density in children after a long-term glucocorticoids treatment.

Treatment with glucocorticoids is associated with lower bone mineral density (BMD). We performed a genome-wide association study to analyze interactive effects between genotypes and cumulative dose of prednisone (PD) over 4.3 years of follow-up period on the final BMD Z-scores in 461 white children from the Childhood Asthma Management Program. No variants met the conventional criteria for genome-wide significance, and thus we looked for evidence of replication. The top 100-ranked single-nucleotide polymorphisms (SNPs) were then carried forward replication in 59 children with acute lymphoblastic leukemia (ALL) exposed to large fixed doses of PD as part of their chemotherapeutic regimen. Among them, rs6461639 (interaction P=1.88 × 10-5 in the CAMP population) showed a significant association with the final BMD Z-scores in the ALL population (P=0.016). The association of the ALL population was only present after correction for the anti-metabolite treatment arm (high vs low dose). We have identified a novel SNP, rs6461639, showing a significant effect on the final BMD Z-scores in two independent pediatric populations after long-term high-dose PD treatment.

Bone mineral density among long-term survivors of childhood acute lymphoblastic leukemia: results from the St. Jude Lifetime Cohort Study.

BACKGROUND: The prevalence of low bone mineral density (BMD) in adult survivors of childhood acute lymphoblastic leukemia (ALL), and the degree of recovery or decline, are not well elucidated. PROCEDURE: Study subjects (age ≥ 18 years and ≥10 years post-diagnosis) participated in an institutional follow-up protocol and risk-based clinical evaluation based on Children's Oncology Group guidelines. Trabecular volumetric BMD was ascertained using quantitative computed tomography, reported as age- and sex-specific Z-scores. RESULTS: At median age 31 years, 5.7% of 845 subjects had a BMD Z-score of ≤-2 and 23.8% had a Z-score of -1 to -2. Cranial radiation dose of ≥24 Gy, but not cumulative methotrexate or prednisone equivalence doses, was associated with a twofold elevated risk of a BMD Z-score of ≤-1. The cranial radiation effect was stronger in females than in males. In a subset of 400 subjects, 67% of those who previously had a BMD Z-score of ≤-2 improved by one or more categories a median of 8.5 years later. CONCLUSIONS: Very low BMD was relatively uncommon in this sample of adult survivors of childhood ALL, and BMD Z-scores tended to improve from adolescence to young adulthood. High-dose cranial or craniospinal radiation exposure was the primary predictor of suboptimal BMD in our study. Given that cranial radiation treatment for childhood ALL is used far more sparingly now than in earlier treatment eras, concerns about persistently low BMD among most current childhood ALL patients may be unwarranted.

Calcium and cholecalciferol supplementation provides no added benefit to nutritional counseling to improve bone mineral density in survivors of childhood acute lymphoblastic leukemia (ALL).

BACKGROUND: We sought to improve lumbar spine bone mineral density (LS-BMD) in long-term survivors of childhood acute lymphoblastic leukemia (ALL) using calcium and cholecalciferol supplementation. PROCEDURE: This double-blind, placebo-controlled trial randomized 275 participants (median age, 17 [9-36.1] years) with age- and gender-specific LS-BMD Z-scores <0 to receive nutritional counseling with supplementation of 1,000 mg/day calcium and 800 International Unit cholecalciferol or placebo for 2 years. The primary outcome was change in LS-BMD assessed by quantitative computerized tomography (QCT) at 24 months. Linear regression models were employed to identify the baseline risk factors for low LS-BMD and to compare LS-BMD outcomes. RESULTS: Pre-randomization LS-BMD below the mean was associated with male gender (P = 0.0024), White race (P = 0.0003), lower body mass index (P < 0.0001), and cumulative glucocorticoid doses of ≥ 5,000 mg (P = 0.0012). One hundred eighty-eight (68%) participants completed the study; 77% adhered to the intervention. Mean LS-BMD change did not differ between survivors randomized to supplements (0.33 ± 0.57) or placebo (0.28 ± 0.56). Participants aged 9-13 years and those 22-35 years had the greatest mean increases in LS-BMD (0.50 ± 0.66 and 0.37 ± 0.23, respectively). Vitamin D insufficiency (serum 25[OH]D <30 ng/ml) found in 296 (75%), was not associated with LS-BMD outcomes (P = 0.78). CONCLUSION: Cholecalciferol and calcium supplementation provides no added benefit to nutritional counseling for improving LS-BMD among adolescent and young adult survivors of ALL (93% of whom had LS-BMD Z-scores above the mean at study entry).

Clinical utility and implications of asparaginase antibodies in acute lymphoblastic leukemia.

Hypersensitivity to asparaginase is common, but the differential diagnosis can be challenging and the diagnostic utility of antibody tests is unclear. We studied allergic reactions and serum antibodies to E. coli asparaginase (Elspar) in 410 children treated on St. Jude Total XV protocol for acute lymphoblastic leukemia. Of 169 patients (41.2%) with clinical allergy, 147 (87.0%) were positive for anti-Elspar antibody. Of 241 patients without allergy, 89 (36.9%) had detectable antibody. Allergies (P=0.0002) and antibodies (P=6.6 × 10(-6)) were higher among patients treated on the low-risk arm than among those treated on the standard/high-risk arm. Among those positive for antibody, the antibody titers were higher in those who developed allergy than in those who did not (P<1 × 10(-15)). Antibody measures at week 7 of continuation therapy had a sensitivity of 87-88% and a specificity of 68-69% for predicting or confirming clinical reactions. The level of antibodies was inversely associated with serum asparaginase activity (P=7.0 × 10(-6)). High antibody levels were associated with a lower risk of osteonecrosis (odds ratio=0.83; 95% confidence interval, 0.78-0.89; P=0.007). Antibodies were related to clinical allergy and to low systemic exposure to asparaginase, leading to lower risk of some adverse effects of therapy.

Osteonecrosis in children after allogeneic hematopoietic cell transplantation: study of prevalence, risk factors and longitudinal changes using MR imaging.

Osteonecrosis after hematopoietic SCT (HCT) has seldom been addressed in pediatric populations. At our institution, since January 2002, children undergoing allogeneic HCT (alloHCT) receive yearly follow-up magnetic resonance imaging (MR) of hips and knees. To estimate the prevalence, longitudinal changes and associated risk factors for osteonecrosis after alloHCT, we reviewed MRs for children who underwent single alloHCT during the study period. We analyzed 149 of 344 patients who had post-HCT MR imaging performed (84 males; median age 11 years (range, 0.5-21 years)), median follow-up time was 32.6 months (range, 2.8-97.2 months). In all, 44 (29.5%) developed osteonecrosis of hips and/or knees; of those, 20 (45%) had at least 30% epiphyseal involvement. In 23 (52%), osteonecrosis lesions were identified in the first and in 43 (98%) by the third yearly scan. Knees were more frequently involved than hips; severity of osteonecrosis was greater in hips. Those who had pre-alloHCT osteonecrosis, two patients' hips and six patients' knees resolved completely; three patients' osteonecrosis lesions regressed after alloHCT. On risk factor analysis, age at time of alloHCT (P=0.051) and osteonecrosis identified by MRs before alloHCT (P=0.001) were the primary risk factors. This analysis shows that preventive strategies for osteonecrosis in this population should focus on measures to minimize risk factors before alloHCT.

Prevalence of osteonecrosis and associated risk factors in children before allogeneic BMT.

Osteonecrosis (ON) is a debilitating long-term complication of allogeneic BMT (allo-BMT), but may begin before allo-BMT in some children because of their primary disease treatment. Therefore, to estimate the prevalence and associated risk factors for ON before allo-BMT, we conducted a retrospective analysis of magnetic resonance (MR) studies of 118 children who underwent first allo-BMT at our institution between December 2000 and September 2007. Of the 118 consecutive patients, 107 (90.7%) underwent prospective MR studies irrespective of symptoms (69 males; median age at allo-BMT 12.9 years), and 11 underwent MR studies for symptoms. Among the 107 who had prospective imaging, 23 (21.5%) had ON; nearly 50% had at least 30% epiphyseal involvement. Knees were more frequently involved than were hips; severity of ON was greater in hips. ON prevalence before allo-BMT was 23.72% when all 118 patients were included in the denominator. Risk factor analysis, limited to MR studies performed irrespective of symptoms, revealed female gender (P=0.049) and age 10 years at the time of MR study (P=0.03) as significant risk factors, and primary diagnosis of lymphoid malignancies and aplastic anemia trended toward significance. ON before allo-BMT is a common occurrence in children.

How does osteonecrosis about the knee progress in young patients with leukemia?: a 2- to 7-year study.

BACKGROUND: Osteonecrosis is a major treatment complication of pediatric leukemias owing to its potential to cause joint deterioration. Because of potential long-term effects of osteonecrosis on joints, information regarding its progression and collapse in different patients can be used to identify high-risk groups, advise the patients and parents of this complication, and potentially consider the risk for development of osteonecrosis in planning primary treatment. QUESTIONS/PURPOSES: We therefore determined: (1) the incidence of joint collapse and/or pain in young patients with hematologic malignancies diagnosed with ON of the knee; (2) risk factors associated with collapse; and (3) the relationship between size and location of osteonecrotic knee lesions and the likelihood of joint collapse. PATIENTS AND METHODS: We retrospectively reviewed 109 patients with hematologic malignancies and MRI-confirmed knee osteonecrosis. The median age was 11.5 years (range, 2.3-18.8 years) at primary diagnosis of hematologic malignancy and a median age of 13.4 years (range, 2.7-23.3 years) at diagnosis of osteonecrosis of the knee. For analyses, we used the first and last MR images. Minimum clinical followup was 2.3 years after diagnosis of knee osteonecrosis (median, 6 years; range, 2.3-7.17 years). RESULTS: Joint collapse occurred in 22% (24 of 109). Older age, pain at osteonecrosis presentation, and lesions extending to the articular surface of distal femoral epiphyses were associated with joint collapse. CONCLUSIONS: Younger patients and those without extensive femoral epiphyseal involvement have a better prognosis for osteonecrosis of the knee. LEVEL OF EVIDENCE: Level II, prognostic study. See the Guidelines for Authors for a complete description of levels of evidence.

Asymptomatic kidney stones in long-term survivors of childhood acute lymphoblastic leukemia.

We hypothesized an association between renal calculi and bone mineral density (BMD) deficits, shown in adults, exists in survivors of childhood acute lymphoblastic leukemia (ALL). Thus, we analyzed the associations between quantitative computed tomography (QCT)-determined renal calcifications and clinical parameters (gender, race, age at diagnosis and age at the time of QCT), BMD, treatment exposures and Tanner stage. We investigated the associations between stone formation and nutritional intake, serum and urinary calcium and creatinine levels, and urinary calcium/creatinine ratio. Exact chi(2)-test was used to compare categorical patient characteristics, and the Wilcoxon-Mann-Whitney test to compare continuous measurements. Of 424 participants, 218 (51.4%) were males; 371 (87.5%) were nonblack. Most (n=270; 63.7%) were >or=3.5 years at ALL diagnosis. Mean (s.d.) and median (range) BMD Z-scores of the entire cohort were -0.4 (1.2) and -0.5 (-3.9 to 5.1), respectively. Nineteen participants (10 males; 10 Caucasians) had kidney stones (observed prevalence of 4.5%; 19/424) with a significant negative association between stone formation and body habitus (body mass index, P=0.003). Stone formation was associated with treatment protocol (P=0.009) and treatment group (0.007). Thus, kidney stones in childhood ALL survivors could herald the future deterioration of renal function and development of hypertension. Long-term follow-up imaging may be warranted in these patients to monitor for progressive morbidity.

Ultrasonic characterization of cancellous bone using apparent integrated backscatter.

Apparent integrated backscatter (AIB) is a measure of the frequency-averaged (integrated) backscattered power contained in some portion of a backscattered ultrasonic signal. AIB has been used extensively to study soft tissues, but its usefulness as a tissue characterization technique for cancellous bone has not been demonstrated. To address this, we performed measurements on 17 specimens of cancellous bone over two different frequency ranges using a 1 MHz and 5 MHz broadband ultrasonic transducer. Specimens were obtained from bovine tibiae and prepared in the shape of cubes (15 mm side length) with faces oriented along transverse (anterior, posterior, medial and lateral) and longitudinal (superior and inferior) principal anatomic directions. A mechanical scanning system was used to acquire multiple backscatter signals from each direction for each cube. AIB demonstrated highly significant linear correlations with bone mineral density (BMD) for both the transverse (R2 = 0.817) and longitudinal (R2 = 0.488) directions using the 5 MHz transducer. In contrast, the correlations with density were much weaker for the 1 MHz transducer (R2 = 0.007 transverse, R2 = 0.228 longitudinal). In all cases where a significant correlation was observed, AIB was found to decrease with increasing BMD.

Dental abnormalities in children preparing for pediatric bone marrow transplantation.

The purpose of our study was to describe the types and frequencies of altered dental development in pediatric patients preparing for bone marrow transplantation (BMT). Retrospective review of the medical records and panoramic radiographs of all patients who underwent BMT at St Jude Children's Research Hospital between 1990 and 2000 for whom pre-BMT dental examination and panoramic radiography records were available. All patients were treated on institutional protocols. We recorded patient demographics and radiographic evidence of microdontia, hypodontia, taurodontia, root stunting, caries, enamel pearls, and pulpal calcifications. The 259 patients identified (150 male and 109 female) had a median age of 12.82 years (range, 3.18-25.93 years) at the time of BMT. In total, 203 were Caucasian, 38 were African-American, and 18 were of other races. In all, 150 (57.9%) had abnormal dentition. The most common dental abnormalities were caries (n=84), pulpal calcifications (n = 34), and dental extractions (n = 33). Developmental abnormalities occurred less frequently: taurodontia (n = 8), hypodontia (n = 10), microdontia (n = 11), and root stunting (n = 11). Dental abnormalities are prevalent in children undergoing BMT. Pre-transplant oral hygiene and dental examination should be standard care in order to minimize potential sites of infection.

Dental abnormalities after pediatric bone marrow transplantation.

Our purpose was to describe the types and frequencies of altered dental development in pediatric patients following bone marrow transplantation (BMT). A retrospective review of the medical records and panoramic radiographs of all patients who underwent BMT at St Jude Children's Research Hospital between 1990 and 2000, for whom pre-BMT and post-BMT dental examination and panoramic radiography records were available, is presented. All patients were treated on institutional protocols. We recorded patient demographics and radiographic evidence of microdontia, hypodontia, taurodontia, root stunting, caries, enamel pearls, dental restorations/extractions and pulpal calcification. The 99 patients identified (52 males, 47 females) had a median age of 13.5 years (range, 3.4-25.9 years) at the time of BMT. In all, 73 were Caucasian, 15 were African-American, and 11 were of other races. The frequency of radiographically evident root stunting in permanent teeth was significantly increased after BMT (P<0.001), but there was no significant change in the frequency of other dental abnormalities after BMT. Dental abnormalities are prevalent in survivors of childhood BMT, but only root stunting appeared to progress with BMT.

Bone mineral density and osteonecrosis in survivors of childhood allogeneic bone marrow transplantation.

Our purpose was to evaluate frequency and severity of bone mineral decrements and frequency of osteonecrosis in survivors of pediatric allogeneic bone marrow transplantation (alloBMT). We retrospectively reviewed demographic information, treatment, magnetic resonance (MR) imaging studies (hips and knees), and bone mineral density (BMD) studies of 48 patients as measured by quantitative computed tomography (QCT). In all, 24 patients were male; 37 were Caucasian. Median age at alloBMT was 10.3 years (1.6-20.4 years). Of the 48 patients, 43 underwent QCT. Median time between alloBMT and imaging was 5.1 years (1.0-10.2 years). Median BMD Z-score was -0.89 (-4.06 to 3.05). BMD Z-score tended to be associated with female sex (P=0.0559) but not with age at BMT, race, primary diagnosis, time from alloBMT, T-cell depletion of graft, total-body irradiation, or acute/chronic graft-versus-host disease (GVHD). MR showed osteonecrosis in 19 of 43 (44%). We found no associations between osteonecrosis and sex, race, diagnosis, age at BMT, history of GVHD, time from BMT, or T-cell depletion. Seven patients (15%) had MR changes of osteonecrosis and BMD Z-scores of less than -1 s.d. We conclude that pediatric alloBMT survivors have decreased BMD and are at risk of osteonecrosis. They should be monitored to assure early intervention that may ameliorate adverse outcomes.

Dynamic magnetic resonance imaging of regional contrast access as an additional prognostic factor in pediatric osteosarcoma.

BACKGROUND: The purpose of this article was to evaluate the utility of a pharmacokinetically modeled measure of regional contrast access, based on dynamic contrast-enhanced magnetic resonance imaging (MRI) studies after preoperative chemotherapy, as a predictor of disease free survival in osteosarcoma. METHODS: The kinetic parameters of a two-compartment pharmacokinetic model of MRI contrast agent accumulation were analyzed in relation to disease free survival in 31 patients who received protocol-based therapy for nonmetastatic osteosarcoma of the extremities. The modeled exchange rate of contrast between the plasma and the tumor extravascular extracellular fluid space served as a measure of regional contrast access. The prognostic impact of both the clinically accepted standard of histologic evaluation of tumor necrosis and the regional contrast access were analyzed with tumor size as an influential factor. RESULTS: Although the histologic grade of response was not a statistically significant prognostic factor in these patients (P = 0.884), regional contrast access after preoperative chemotherapy was significantly predictive of disease free survival (P = 0.035) in the Cox proportional hazards model. Lower regional access before surgery and smaller tumor size were associated with a better treatment outcome. Log-rank analyses of Kaplan-Meier curves indicated that the impact of regional access was most pronounced in patients with larger tumors (P = 0.052). Higher regional access at presentation also was associated significantly with greater decreases during therapy. CONCLUSIONS: Dynamic MRI estimates of regional contrast access after preoperative chemotherapy, when combined with tumor size, holds promise for the early identification of patients at risk of recurrence. The availability of such response predictors could facilitate the development of risk-adapted treatment approaches.

Magnetic resonance imaging detection of avascular necrosis of the bone in children receiving intensive prednisone therapy for acute lymphoblastic leukemia or non-Hodgkin lymphoma.

The purpose of this study was to determine the frequency with which magnetic resonance (MR) imaging detects avascular necrosis of the bone (AVNB) in children with acute lymphoblastic leukemia (ALL) or advanced-stage non-Hodgkin lymphoma (NHL) who receive prednisone during remission induction, reinduction, and maintenance chemotherapy; to assess the clinical significance of these findings; and to identify factors predictive of AVNB. We prospectively obtained MR imaging of the hips and knees of 116 children who had completed at least 1 year of treatment for ALL or advanced-stage NHL on identical prednisone-containing regimens between December 1991 and October 1994. MR imaging findings of AVNB were compared with clinical outcomes, and the effect of therapeutic and patient factors on the frequency of AVNB was analyzed. The MR imaging findings of 17 of the 116 participating patients were consistent with AVNB. The most common clinical manifestation was joint pain (11 patients). Only one patient had progressive joint deterioration that necessitated surgical replacement. Only age 10 years or more at the time of the primary diagnosis was significantly associated with the development of AVNB (P = 0.004). MR imaging showed changes consistent with AVNB in approximately 15% of this patient population. However, most patients in this study who had MR imaging signs of AVNB did not experience progressive joint destruction, even with continued prednisone therapy. Therefore, the clinical usefulness of MR imaging as a screening tool for AVNB in this set of patients remains uncertain.

Bone mineral decrements in survivors of childhood acute lymphoblastic leukemia: frequency of occurrence and risk factors for their development.

We assessed the clinical and treatment factors that predispose survivors of childhood acute lymphoblastic leukemia (ALL) to low bone mineral density (BMD). Using quantitative computed tomography, we determined the frequency of low BMD (defined as >1.645 standard deviations (SD) below the mean) in leukemia survivors treated with multiagent chemotherapy including prednisone and antimetabolite. All participants had completed therapy at least 4 years earlier, remained in continuous complete remission, and had no second malignancies. We statistically correlated BMD results with patient characteristics and treatment histories. Among 141 survivors (median age, 15.9 years; median time after diagnosis, 11.5 years), median BMD z score was -0.78 SD (range, -3.23 to 3.61 SDs). Thirty participants (21%; 95% confidence interval, 15% to 29%) had abnormally low BMD, a proportion significantly (P < 0.0001) greater than the expected 5% in normal populations. Risk factors for BMD decrements included male sex (P = 0.038), Caucasian race (P < 0.0001), and cranial irradiation (P= 0.0087). BMD inversely correlated with cranial irradiation dose. BMD z scores of patients who received higher doses of antimetabolites were lower than those of other patients. Childhood ALL survivors are at risk to have low BMD, especially males, Caucasians, and those who received cranial irradiation.

Thallium bone imaging as an indicator of response and outcome in nonmetastatic primary extremity osteosarcoma.

PURPOSE: We investigated one 201Tl bone scintigraphy method as a predictor of histologic response and event-free survival (EFS) of nonmetastatic extremity osteosarcoma. MATERIALS AND METHODS: We evaluated images of the primary tumor to determine whether they exhibited a donut of avidity for 40 patients enrolled on a single institutional protocol. Participants underwent three serial 201Tl bone scintigraphy studies during preoperative neoadjuvant chemotherapy. Intra- and interobserver variability of the method was assessed, and the presence of the donut of avidity was examined as a predictor of EFS and histologic response. RESULTS: Fifty-three percent of patients were female and 75% were Caucasian; the median age at diagnosis was 13.5 years. Intraobserver agreement was moderate to very good, ranging from 0.595 to 0.865. Interobserver agreement was moderate to good for all time points, ranging from 0.576 to 0.708. There was a significant difference in EFS among patients with and without the donut-shape at any of the three time points (P = 0.049); patients whose tumors displayed a donutshape had inferior EFS. CONCLUSION: The pattern of donut avidity in extremity OS is a predictor of lower EFS, but does not correlate with histologic response to therapy.

Prognostic factors and imaging patterns of recurrent pulmonary nodules after thoracotomy in children with osteosarcoma.

BACKGROUND: In children with osteosarcoma who have undergone thoracotomy, it often is difficult to distinguish metastatic from benign recurrent pulmonary nodules. The authors of this study sought to identify any computed tomography (CT) imaging pattern of recurrent pulmonary metastases in this patient population. The authors also sought to identify associated prognostic factors. METHODS: CT scans obtained after thoracotomy were available for 35 patients with osteosarcoma who had undergone resection of presumed pulmonary metastases at St. Jude Children's Research Hospital (Memphis, TN). CT scans obtained before the initial thoracotomy were available for 33 of the 35. The authors recorded location, histologic diagnosis, and time of development of the original pulmonary nodules, time of recurrence of pulmonary disease; the location of recurrent nodules, and the presence of calcification, adenopathy, or progressive pleural disease, as well as patient demographic data, survival data, and location of the primary tumor site. RESULTS: Pulmonary nodules recurred in 32 of the 35 patients after thoracotomy. Nineteen of these patients underwent resection of the recurrent lesions and 1 who died underwent an autopsy; 18 of the 20 patients had metastatic disease. The only CT finding consistently associated with recurrent metastatic disease was progressive pleural thickening, which predicted a poor outcome. The occurrence of a solitary pulmonary nodule in the lung contralateral to the previous surgery was associated almost always with a benign process. CONCLUSIONS: CT imaging cannot distinguish reliably between benign and metastatic recurrent pulmonary disease after thoracotomy in patients with osteosarcoma. Recurrent pulmonary disease in this set of patients is likely to be metastatic, and aggressive surgical intervention is probably warranted. In this study, patients who had progressive pleural disease after thoracotomy consistently experienced pulmonary metastatic recurrence and had a poor prognosis.

Metastatic osteosarcoma to the liver after treatment for synovial sarcoma: a case report.

Metastatic osteosarcoma most commonly affects the lungs and other bones. Hepatic metastasis at the time of diagnosis is extremely rare. A 14-year-old boy with synovial sarcoma of the left popliteal fossa was treated with surgical resection, radiotherapy for microscopic residual disease, and 1 year of chemotherapy (vincristine, cyclophosphamide, dactinomycin, and doxorubicin). Approximately 10 years after the initial diagnosis, a secondary osteosarcoma developed in the left proximal tibia. Computed tomography at presentation showed bilateral pulmonary metastases and large ossified nodules in the liver that demonstrated abnormal avidity on 99mTc MDP bone scan indicating hepatic metastasis. Despite chemotherapy (cisplatin, ifosfamide, high-dose methotrexate, and dacarbazine), the patient died of progressive disease 4 months after the diagnosis of the second cancer. Hepatic metastasis was found at the time of diagnosis of a secondary osteosarcoma and manifested as ossified nodules. The risk of radiation-induced osteosarcoma should always be considered in decisions about treatment for soft-tissue sarcoma.

Complications of limb-sparing procedures using endoprosthetic replacements about the knee for pediatric skeletal sarcomas.

Ninety-five percent of bone tumors are now managed with limb-sparing techniques. For pediatric patients with bone cancer, such limb reconstruction techniques often involve the placement of large endoprosthetic devices with the goal of improving survivors' quality of life. Nevertheless, few radiologic publications discuss the use of these techniques in children and adolescents. This pictorial essay describes the imaging characteristics of the complications associated with endoprosthetic devices and discusses the conditions that may simulate them.

Reversal of optic canal stenosis in osteopetrosis after bone marrow transplant.

PURPOSE: To describe a patient with infantile osteopetrosis and optic atrophy secondary to optic canal stenosis who demonstrated optic canal enlargement after bone marrow transplant. METHODS: Case report. A 3-month-old infant with infantile "malignant" osteopetrosis underwent ophthalmic examination, including visual evoked potentials, electroretinogram, and computed tomography (CT). Bone marrow transplant was performed at 8 months of age. RESULTS: Examination revealed visual loss and optic atrophy, left eye greater than right eye, secondary to optic canal stenosis. Flash visual evoked potentials revealed a normal waveform in both eyes with increased latency in the left eye. Electroretinogram was normal in both eyes. CT after bone marrow transplant showed enlargement of the optic canals. Vision remains stable 43 months after bone marrow transplant. CONCLUSIONS: Bone marrow transplant in infantile osteopetrosis may be followed by reversal of optic canal stenosis and preservation of vision.