CNS and spinal tumors.

Primary CNS tumors consist of a diverse group of neoplasms originating from various cell types in the CNS. Brain tumors are the most common solid malignancy in children under the age of 15 years and the second leading cause of cancer death after leukemia. The most common brain neoplasms in children differ consistently from those in older age groups. Pediatric brain tumors demonstrate distinct patterns of occurrence and biologic behavior according to sex, age, and race. This chapter highlights the imaging features of the most common tumors that affect the child's CNS (brain and spinal cord).

Retained surgical stents as a cause of biliary obstruction in pediatric liver transplants.

BACKGROUND: Small-caliber plastic stents are sometimes placed across the hepaticojejunostomy in liver transplant recipients at the time of biliary reconstruction. These stents usually pass spontaneously, but they can be retained and, rarely, this may cause biliary obstruction. OBJECTIVE: The purpose of this paper is twofold: to describe the appearance of biliary tract obstruction caused by retained surgical stents in pediatric liver transplants, and to report how these stents can be removed using interventional radiology techniques. MATERIALS AND METHODS: Three pediatric patients presenting with biochemical and imaging evidence of biliary obstruction were encountered over a 6-month period. At percutaneous cholangiography all patients were found to have retained surgical stents which appeared to be causing biliary tract obstruction. Percutaneous snaring of the stents was undertaken. RESULTS: All stents were successfully removed using interventional radiology techniques, and follow-up showed no evidence of recurrent obstruction. CONCLUSION: Surgical stents in children undergoing hepaticojejunostomy may be retained and cause biliary obstruction. Radiologists involved with imaging these patients should be aware of this potential cause of biliary obstruction. This complication is amenable to interventional radiology techniques with good long-term results. There is no easy endoscopic or surgical treatment option in these patients.

Neurofibromas with imaging characteristics resembling vascular anomalies.

OBJECTIVE: Although neurofibromas are rare, their initial clinical and imaging presentation can mimic those of vascular anomalies, particularly if the characteristic clinical features of neurofibromatosis are not present. The diagnostic challenges encountered in five cases of histologically proven neurofibromas, initially diagnosed as vascular anomalies, are reviewed and discussed. CONCLUSION: The clinical and imaging differences between neurofibromas and vascular anomalies are detailed with the histopathologic features to better understand why some neurofibromas are diagnosed as vascular anomalies.

Long-term central venous access in pediatric patients at high risk: conventional versus antibiotic-impregnated catheters.

PURPOSE: To study selective use of antibiotic-impregnated catheters in children at increased risk of venous catheter-related infections (CRIs). MATERIALS AND METHODS: From December 2008 to June 2009, 428 peripherally inserted central catheters (PICCs) were placed by the interventional radiology service of a large metropolitan children's hospital. This retrospective study analyzed demographic and outcome data for the 125 patients in this group at high risk for venous CRI. Patients at high risk were those with active systemic infection, previous complicated central venous access, intensive care unit (ICU) admission, intestinal failure, transplantation, complex congenital heart disease, or renal failure. Patients (age, 7.6 y ± 7.0; 73 male and 52 female) received a conventional or antibiotic-impregnated PICC, with 17 receiving more than one catheter. RESULTS: Of the 146 of 428 qualifying patient encounters (34%), 53 patients received an antibiotic-impregnated PICC and 93 received a conventional PICC, representing 5,080 total catheter-days (CDs). The rates of CRIs per 1,000 CDs, including catheter exit site infections and catheter-related bloodstream infections, were 0.86 for antibiotic-impregnated PICCs and 5.5 for conventional PICCs (P = .036). A propensity-based model predicts 15-fold greater infection-free survival over the lifetime of the catheter in patients who receive an antibiotic-impregnated PICC (P < .001). Antibiotic-impregnated PICC recipients with active infection or ICU admission at the time of insertion had no catheter-associated infections, compared with 3.42 and 9.46 infections per 1,000 CDs, respectively, for patients who received conventional PICCs. Patients with intestinal failure had 1.49 and 10 infections per 1,000 CDs with antibiotic-impregnated versus conventional PICCs, respectively. CONCLUSIONS: Antibiotic-impregnated long-term PICCs significantly improve infection-free catheter survival in pediatric patients at high risk.

Idiopathic acute transverse myelitis in children: an analysis and discussion of MRI findings.

BACKGROUND: There is lack of reported magnetic resonance imaging (MRI) studies of idiopathic acute transverse myelitis (ATM) in children. OBJECTIVE: To describe the imaging features of idiopathic ATM in children. METHODS: We retrospectively analyzed the spinal MRI findings of children diagnosed with ATM. The anatomic regions, vertebral segmental length, gray or white matter involvement, cord expansion and gadolinium enhancement were examined. RESULTS: A total of 27 children were diagnosed with isolated monophasic ATM with a mean follow-up of 5.2 years. Two children later diagnosed with neuromyelitis optica were excluded from the pediatric ATM cohort. None of the patients had a subsequent diagnosis of multiple sclerosis. The mean age of onset was 9.5 years (0.5-16.9 years). Spinal MRIs were abnormal in 21 (78%). The mean interval between symptom onset and the MRI was 1.7 days (0-19 days). Central cord hyperintensity involving gray matter was seen in all patients. A majority (67%) of the patients demonstrated long segment lesions with a mean segment length of 6.4. CONCLUSIONS: We conclude that central cord inflammation extending over three or more segments is the most common finding of idiopathic monophasic transverse myelitis in children. The risk of multiple sclerosis in children who experience isolated transverse myelitis as a first demyelinating event is low.

Transgluteal approach for draining pelvic fluid collections in pediatric patients.

PURPOSE: To evaluate a transgluteal approach for draining pelvic fluid collections in pediatric patients. MATERIALS AND METHODS: Institutional review board approval and informed consent for interventional procedures were obtained. From September 1995 to December 2002, 140 abdominopelvic fluid collections were drained at two institutions. Retrospective analysis of a prospectively gathered procedural database revealed that a transgluteal approach was used to drain 53 of these 140 collections (38%) in 51 patients (29 female, 22 male; mean age, 11.2 years; age range, 0.2-19 years). All patients received antibiotics before the procedure. A retrospective analysis was conducted of the patients' medical records and diagnostic imaging and interventional procedure findings, including the reason for referral; location, volume, and character of collections; method and equipment used for evacuation; duration of therapy; evidence of complications; results of microbiologic examination of specimens; and success rates. RESULTS: Transgluteal drainage was performed with computed tomographic (CT) guidance in 45 of the 53 collections (85%), with fluoroscopic guidance in three (6%), and with a combination of both modalities in five (9%). A drainage catheter was successfully placed in 49 collections; four small collections were aspirated without drain placement. Infected fluid was obtained from 41 collections, and serosanguineous fluid was obtained from 12 collections. The mean volume aspirated was 80 mL (2-600 mL). A positive culture was obtained at 28 of the 53 procedures. The mean duration of catheter placement was 4 days (range, 2-14 days). There were no major complications. CONCLUSION: The transgluteal approach to the drainage of abdominopelvic fluid collections with imaging guidance is safe and effective.

CT-guided percutaneous lung biopsy in children.

PURPOSE: To describe techniques and evaluate outcomes of computed tomography (CT)-guided percutaneous lung biopsy in children. MATERIALS AND METHODS: Between April 1992 and June 2003, 64 patients (32 male, 32 female) with a mean age of 10.8 years (0.6-20 years) were referred for 75 lung biopsies. Most biopsies were performed for suspected malignancy (n = 24; 32%) or to distinguish posttransplantation lymphoproliferative disorder from fungal infection in immunocompromised patients (n = 17; 23%). All children referred to the pediatric interventionalists in two children's hospitals for CT-guided biopsy of parenchymal or pleural-based lesions in the thorax were studied. Prospectively gathered procedural data were reviewed for medical history and indications for procedure, admission status, type of anesthesia, technical approach (core vs aspiration biopsy), procedural modifications, lesion size, number of passes required, and immediate complications. Medical records were retrospectively reviewed for diagnostic outcome, impact on patient management, and delayed complications. RESULTS: Procedures were performed under deep sedation whenever possible (n = 61; 81%) with use of a coaxial core biopsy technique (n = 56; 75%), a fine needle aspiration biopsy technique (n = 15; 20%), or both (n = 4; 5%). Mean lesion diameters were 2.5 cm (range, 1-10 cm) in the core biopsy group and 1.0 cm (range, 0.5-1.7 cm) in the aspiration biopsy group. Sixty-four biopsies (85%) were diagnostic. There was one major complication (1.3%), a tension pneumothorax treated with intraprocedural placement of a chest tube. CONCLUSION: Percutaneous CT-guided lung biopsy is a safe and accurate diagnostic procedure in children that obviates open surgical biopsy in most patients.

Oropharyngeal fetus in fetu.

Fetus in fetu is an extremely rare entity and refers to the growth of a "parasitic" twin within a more mature fetus due to its inclusion within cells of the blastocyst. The presence of a vertebral column is considered essential for the diagnosis of a fetus in fetu. The retroperitoneum is the most common location for a fetus in fetu and its location in the mouth is rare. We report a case of oropharyngeal mass detected on antenatal sonography with imaging features consistent with a fetus in fetu. Complete surgical removal of the mass was aided by imaging. Follow-up of these patients is recommended to detect the rare incidence of malignant degeneration.

Transmural migration of gastrostomy tube retention discs.

BACKGROUND: Accidental dislodgment is one of the most frequent causes of avoidable cost and consternation related to gastrostomy tubes. The Sacks-Vine gastrostomy tube, inserted in an antegrade fashion by a percutaneous technique, is extremely stable due to the construction of its disc retention device. However, transmural migration of the retention disc is a known severe delayed complication associated with this tube. OBJECTIVE: To review the presentation, diagnosis, and treatment of transmural migration of gastrostomy retention discs, to propose a mechanism for the progressive development of this complication, and to recommend a method for preventing its occurrence. MATERIALS AND METHODS: From January 1991 to October 1999, pediatric interventional radiologists at two children's hospitals performed 300 antegrade gastrostomy and gastrojejunostomy primary insertion procedures. A "push-pull" variation of the antegrade approach used for 44 of these insertions is excluded from further analysis. Of the remaining 256 procedures, 5 boys and 3 girls with a mean age of 5.1 years (range 0.8-19 years) were identified from review of the prospectively gathered procedural database with significant complications related to the disc retention component of their gastrostomy tubes. A retrospective analysis was conducted of their medical records, diagnostic imaging, and interventional and surgical findings. RESULTS: Transmural migration was diagnosed on average 36 months after insertion (16-48 months). The diagnosis was made incidentally during endoscopy (n=1) or fluoroscopy (n=5) in six asymptomatic patients, and during barium enema to explore feculent vomiting and halitosis in two symptomatic patients. Migration of the retention disc fell along a continuum from intramural (n=4) to transmural and intracolonic (n=4), with gastric mucosal erosion, extensive granulation and inflammation in all eight patients. Although there was no evidence of free air in any patient, a gastrocolic fistula was demonstrated in four patients and a gastrocolocutaneous fistula in two of four patients with complete transmural migration. Surgical resection of the disc, gastrostomy, and fistula repair if needed was successfully performed in all patients. CONCLUSIONS: Gastrostomy tubes with an internal retention disc are at risk for progressive disc migration into and through the gastric wall, resulting in irretrievable fixation and potential fistula formation. This severe delayed complication results from prolonged traction on the retention disc. Transmural migration may be avoided through improved tube care education, daily disc mobilization, and earlier disc retrieval.

Preradiation chemotherapy in primary high-risk brainstem tumors: phase II study CCG-9941 of the Children's Cancer Group.

PURPOSE: This Children's Cancer Group group-wide phase II trial evaluated the efficacy and toxicity of two chemotherapy arms administered before hyperfractionated external-beam radiotherapy (HFEBRT). PATIENTS AND METHODS: Thirty-two patients with newly diagnosed brainstem gliomas were randomly assigned to regimen A and 31 to regimen B. Regimen A comprised three courses of carboplatin, etoposide, and vincristine; regimen B comprised cisplatin, etoposide, cyclophosphamide, and vincristine. Both arms included granulocyte colony-stimulating factor. Patients were evaluated by magnetic resonance imaging after induction chemotherapy and HFEBRT at a dose of 72 Gy. RESULTS: Ten percent +/- 5% of regimen A patients objectively responded to chemotherapy. For combined induction and radiotherapy, 27% +/- 9% of patients improved. The neuroradiographic response rate for regimen B was 19% +/- 8% for chemotherapy and 23% +/- 9% after HFEBRT. Response rates were not statistically significant between regimens after induction or chemotherapy/HFEBRT. Event-free survival was 17% +/- 5% (estimate +/- SE) at 1 year and 6% +/- 3% at 2 years. Survival was significantly longer among patients who responded to chemotherapy (P <.05). Among patients who received regimen A induction, grades 3 and 4 leukopenia were observed in 50% to 65%, with one toxicity-related death. For regimen B, severe leukopenia occurred in 86% to 100%, with febrile neutropenia in 48% to 60% per course. CONCLUSION: Neither chemotherapy regimen meaningfully improved response rate, event-free survival, or overall survival relative to previous series of patients with brainstem gliomas who received radiotherapy with or without chemotherapy.