Some RUS users using Sen2Cor asked to the RUS support why some bands are not computed after Sen2Cor processing.
Depending on the resolution you have selected when executing sen2cor, some bands are indeed not computed. For example, B8 is only computed when using 10 m resolution. At 20 and 60 meters, you can use the band B8A (with a very similar spectral position). The B10, is never computed since it has no surface information, it is only used for cirrus detection - B10 corresponds to a high atmospheric absorption band.
For further information, please see http://forum.step.esa.int/t/sen2cor-processed-l2a-data-2-bands-missed/1412/8).