Key Points Germ line mutations in MECOM cause a heterogeneous bone marrow failure syndrome with congenital hypomegakaryocytic thrombocytopenia. MECOM-associated syndrome includes various organ malformations with variable penetrance, including radioulnar synostosis.

The incidence of chemotherapy-induced transient hyperglycemia in the present study cohort is comparable to that reported in previous pediatric ALL patients. This finding is interesting in view of the elevated prevalence of obesity and the underlying dietary behaviors in this Hispanic study cohort.

CD95 mutations are associated with loss of regulation of B lymphocytes, which predisposes to systemic autoimmunity including SLE. The P4 family provides a model of the complex genetic and functional interactions that are required for the development of a lupus-like syndrome.

In our cohort of ALL patients, BMI was elevated at diagnosis (mean standardized BMI z-score = 0.22, standard deviation = 1.4) then increased and remained elevated for the entire duration of chemotherapy. Children who were 2-9 years of age at diagnosis began therapy with a substantially lower BMI and remained lower over the course of chemotherapy than patients aged 10-18 years at diagnosis. It will be important for future investigations to explore the biological and behavioral factors that may underlie such differential patterns of BMI change over time.

The most accurate prognostic indicator in patients with musculoskeletal sarcomas is the percentage of tumor necrosis after intraarterial chemotherapy. Magnetic resonance (MR) imaging was evaluated to determine its ability to indicate the percentage of necrosis in musculoskeletal neoplasms after treatment. Fourteen patients with musculoskeletal neoplasms underwent treatment protocols including intraarterial chemotherapy (n = 14), radiation therapy (n = 6), and systemic chemotherapy (n = 14). All patients underwent MR imaging before and after treatment, and all underwent either limb salvage surgery (n = 8) or amputation (n = 6) within 1 week of the last MR examination. Standard unehanced spin-echo T1-, spin-density-, and T2-weighted MR sequences were used. The MR images were compared with the pathologic specimens. On T2-weighted images, the signal intensities of viable tumor, tumor necrosis, edema, hemorrhage, and necrosis overlapped. With the unenhanced spin-echo technique, MR imaging cannot be used to predict the percentage of tumor necrosis in musculoskeletal neoplasms after intraarterial chemotherapy.