ABSTRACT
Background: Total lymphoid irradiation (TLI) is a conditioning regimen in allogeneic hematopoietic stem cell transplantation (allo-HSCT) which may reduce long-term toxicities attributed to other techniques, such as total body irradiation (TBI). At our institution, TLI treatments were first planned with the three-dimensional conformal radiation therapy (3D-CRT) technique and later with volumetric modulated arc therapy (VMAT). With the recent availability of a basic helical tomotherapy (HT), the possible dosimetric gain of the latter for TLI is studied. Materials and methods: 22 pediatric patients were planned for VMAT and HT, prescribed to 8 Gy in 4 fractions. VMAT was planned with template based on a single cost function, using the Monaco treatment planning system (TPS). HT plans were planned using Accuray Precision TPS for a basic HT without the dynamic jaws feature or VOLO-Ultra algorithm. Plan quality was analyzed based on four quality indices, mean and maximum doses to planning target volume (PTV) and organs at risk (OARs), dose gradient and integral doses. Differences were analyzed with Wilcoxon signed-rank test. Results: HT plans resulted in improved conformity (CI) and homogeneity indices (HI) (p < 0.05) but less steep dose gradient (p = 0.181). VMAT plans created larger areas with high doses within the PTV, while comparable doses to OARs, except mainly for the spinal marrow, for which a reduction of 37.7% in D2% was obtained (p < 0.05). Integral dose for non-tumor tissue was 11.3% lower with the VMAT template (p < 0.05). Conclusion: HT achieves better conformity and homogeneity even without its more advanced features. Nevertheless, the VMAT template achieves dosimetric results close to those of HT, both with similar clinical outcome.
ABSTRACT
BACKGROUND: Kaposiform hemangioendothelioma is an uncommon vascular tumor initially reported to occur exclusively in children. METHODS: The presentation, pathologic evaluation, and management of an unusual case of kaposiform hemangioendothelioma is presented and discussed. RESULTS: A 27-year-old HIV-negative man was initially seen with a reddish nodule located in the outer third of the external auditory canal. Histologically, the tumor was composed of spindle-shaped cells arranged in short fascicles associated with small endothelial-like vascular spaces, similar in appearance to Kaposi's sarcoma. The lesion was locally excised but recurred 1 month later; then radiation therapy was performed. The patient remains well at 5-year follow-up. CONCLUSIONS: Recognition of kaposiform hemangioendothelioma is important to avoid possible confusion with a variety of vascular neoplasms with different biologic potential. This case presented some diagnostic difficulty because of the age of the patient and the unusual location of the lesion and had to be mainly distinguished from Kaposi's sarcoma.
