If it's a cane (Angel Wing) it doesn't have a tuber, and if you've got light-starved shoots you'll need to be careful about getting it into the light it so desperately needs to keep it from burning. If you have fluorescents that might be the best treatment, and then move it into brighter light gradually. Cane begonias can take quite a lot of light, including some sun, but would need to be acclimated. If you're gentle with it you should get new shoots at the base and if the ones you have now don't get looking better you can indeed cut them off, but i'd wait until some new growth shows up to do that. In the future, treat it like a regular houseplant and don't expect it to go dormant, as they really don't want to. They make great houseplants all year around.
Another Nancy