Self-limiting sternal tumors of childhood (SELSTOC).

BACKGROUND: Because a sternal mass is often alarming, it is important to identify the clinical features of benign processes. PROCEDURE: Data on clinical presentation, diagnostics, treatment and outcome of pediatric patients presenting with a sternal tumor between 2001 and 2009 were collected from medical records. RESULTS: Among the 1,700 children who were referred to our pediatric-oncology center, 14 presented with a rapidly growing sternal mass. All patients (10 males) were Caucasian and median age was 16 (range: 7-50) months. Reported symptoms were local pain (n = 7) and/or raised body temperature (n = 5). No major preceding traumas were reported. Physical examination revealed solid tumors with a median diameter of 3 (range: 1-4.5) cm in a pre-sternal/para-sternal location. Half of the patients showed red/blue discoloration of the skin. On radiology, dumbbell-shaped lesions extended to the area behind the sternal bone, involving the cartilage, leading to increased distance between ossification centers. Histopathology at diagnosis was available from five patients and showed aspecific chronic or acute inflammation (n = 4) and a reactive osteochondromatous lesion (n = 1). Laboratory infection parameters were not/only slightly raised and microbiologic cultures were negative in all patients. All tumors decreased in size within 1 month, in both patients with and without antibiotics. On physical examination the tumors disappeared within 6 months. CONCLUSIONS: This study reports 14 young children with a rapidly growing sternal mass due to aseptic inflammation, that we named self-limiting sternal tumor of childhood (SELSTOC). To prevent invasive diagnostic interventions and unnecessary treatment, we advocate a wait-and-see approach with close follow-up in the first weeks.

Microrheology and dynamics of an associative polymer.

We study the microscopic viscoelastic properties and relaxation dynamics of solutions of a side-chain associative polymer, hydrophobically modified hydroxyethyl cellulose (hmHEC). Dynamic light scattering from small tracer particles suspended in the polymer solutions is used to determine their viscous and elastic moduli on the scale of the particles. Bulk-scale viscoelastic properties are measured by shear rheometry. The motion of the tracer particles in hmHEC is diffusive at short times and subdiffusive at intermediate and long times. The long-time subdiffusive motion was not observed in parallel experiments on unmodified HEC solutions, and is explained in terms of hindered reptation of the hydrophobically modified polymer chains in the associative network. Dynamic light scattering from the polymer molecules themselves shows that chain relaxation in hmHEC is dominated by slow concentration-dependent processes due to the large-scale associative network structure, while that in HEC is dominated by fast concentration independent Rouse-like dynamics.

Behavior of sink and source defects in a one-dimensional traveling finger pattern.

We present the results of an experimental study of sink and source defects in a one-dimensional pattern of traveling fingers that form at a driven fluid-air interface. We find that sinks and sources behave differently: Sinks separate regions of differing wave number and move smoothly so as to keep the phase difference across the sink fixed. They are transient objects which are eventually destroyed at the boundaries of the experiment or by collision with a source. Sources, on the other hand, are long lived. They are symmetric and stationary on average, although individual sources move erratically and do not display the phase-matching behavior of the sinks.

Spiral patterns in oscillated granular layers.

Cell-filling spiral patterns are observed in a vertically oscillated layer of granular material when the oscillation amplitude is suddenly increased from below the onset of pattern formation into the region where stripe patterns appear for quasistatic increases in amplitude. These spirals are transients and decay to stripe patterns with defects. A transient spiral defect chaos state is also observed. We describe the behavior of the spirals, and the way in which they form and decay. Our results are compared with those for similar spiral patterns in Rayleigh-Bénard convection in fluids.

Development and geometry of isotropic and directional shrinkage-crack patterns.

We have studied shrinkage-crack patterns which form when a thin layer of an alumina/water slurry dries. Both isotropic and directional drying were studied. The dynamics of the pattern formation process and the geometric properties of the isotropic crack patterns are similar to what is expected from recent models, assuming weak disorder. There is some evidence of a gradual increase in disorder as the drying layer become thinner, but no sudden transition, in contrast to what has been seen in previous experiments. The morphology of the crack patterns is influenced by drying gradients and front propagation effects, with sharp gradients having a strong orienting and ordering effect.