<p><strong>BACKGROUND: </strong>Nearly one-third of patients with neurofibromatosis type 1-associated optic pathway glioma (NF1-OPG) fail frontline chemotherapy; however, little is known about risk factors for treatment failure.</p>

<p><strong>METHODS: </strong>We performed a retrospective multi-institutional cohort study to identify baseline risk factors for treatment-refractory/relapsed disease and poor visual outcome in children with NF1-OPG. Refractory/relapsed NF1-OPG was defined as requirement of two or more treatment regimens due to progression or relapse.</p>

<p><strong>RESULTS: </strong>Of 111 subjects eligible for inclusion, adequate clinical and visual data were available for 103 subjects from 7 institutions. Median follow-up from initiation of first chemotherapy regimen was 95 months (range 13-185). Eighty-four (82%) subjects received carboplatin-based frontline chemotherapy. Forty-five subjects (44%) experienced refractory/relapsed disease, with median time of 21.5 months (range 2-149) from initiation of first treatment to start of second treatment. The proportion of patients without refractory/relapsed disease at 2 and 5 years was 78% and 60%. In multivariable analyses, age less than 24 months at initial treatment, posterior tumor location, and familial inheritance were associated with refractory/relapsed NF1-OPG by 2 years. Both age less than 24 months and posterior tumor location were associated with refractory/relapsed NF1-OPG by 5 years. Subjects with moderate to severe vision loss at last follow-up were more likely to have posterior tumor location, optic disc abnormalities, or abnormal visual acuity at initial treatment.</p>

<p><strong>CONCLUSION: </strong>Young age, posterior tumor location, and optic disc abnormalities may identify patients with the greatest likelihood of refractory/relapsed NF1-OPG and poor visual outcomes, and who may benefit from newer treatment strategies.</p>

<p><strong>OBJECTIVES: </strong>To study the trend of Clostridium difficile infection (CDI) and risk factors for hospital acquired CDI (HA-CDI) among children with cancer.</p>

<p><strong>STUDY DESIGN: </strong>We analyzed 33 095 first pediatric hospitalizations for malignancy among 43 pediatric hospitals between 1999 and 2011. The effect of demographics, disease characteristics, and weekly drug exposure (antibiotics, antacids, and chemotherapy) on HA-CDI was assessed with multivariate Cox regression. CDI was defined by the combination of International Classification of Diseases, 9th edition-Clinical Modification (ICD-9CM), CDI diagnostic assay billing code, and concurrent administration of a CDI-active antibiotic. HA-CDI was defined as CDI with assay occurring after the sixth hospital day.</p>

<p><strong>RESULTS: </strong>A total of 1736 admissions with CDI were identified, of which 380 were HA-CDI. CDI incidence increased from 1999-2006 (P = .01); however, CDI testing frequency and disease decreased from 2006-2010 (P &lt; .05). Admissions with HA-CDI had longer lengths of stay compared with those without HA-CDI (35 days vs 12 days, P &lt; .01) and greater risk of inpatient mortality (relative risk 2.3, P &lt; .01). Increased risk of HA-CDI (hazard ratio [95% CI]) was seen after exposure to the following drugs: aminoglycoside (1.357 [1.053-1.749]), third generation cephalosporin (1.518 [1.177-1.959]), cefepime (2.383 [1.839-3.089]), and proton pump inhibiting agent (1.398 [1.096-1.784]) in the prior week, and chemotherapy (1.942 [1.491-2.529]) in the 8-14 days prior to HA-CDI onset. Histamine-2 receptor antagonist exposure in the prior week was associated with decreased risk of HA-CDI (0.730 [0.584-0.912]).</p>

<p><strong>CONCLUSIONS: </strong>Despite an apparent decrease in CDI incidence from 2006-2010, HA-CDI remains prevalent and morbid among children with cancer. Recent exposure to chemotherapy, proton pump inhibitor, and certain antibiotics were independent risk factors for HA-CDI.</p>

<p>Patients with neurofibromatosis type 1 (nf1) are at increased risk for both benign and malignant tumours, and distinguishing the malignant potential of an individual tumour is a common clinical problem in these patients. Here, we review two cases of uncommon malignancies (Hodgkin lymphoma and mediastinal germ-cell tumour) in patients with nf1. Although (18)F-fluorodeoxyglucose positron-emission tomography (fdg-pet) has been used to differentiate benign neurofibromas from malignant peripheral nerve sheath tumours, fdg-pet characteristics for more rare tumours have been poorly described in children with nf1. Here, we report the role of pet imaging in clinical decision-making in each case. In nf1, fdg-pet might be useful in the clinical management of unusual tumour presentations and might help to provide information about the malignant potential of uncommon tumours.</p>