In the 'good old days' they used to radiate hands for rheumatoid arthritis. Apparently it works fairly well. It has fallen out of favor, but considering the significant morbidities associated with some of the hard-core rheumatoid drugs, it doesn't sound like such a bad deal (synovectomy by instillation of a radioactive phosporus isotope is still around, but as an open isotope, it falls under nucmeds scope of practice).
Did an early rad-onc elective this year for 2 weeks and had a renal transplant patient with acute rejection whom we were planning to radiate. Apparently it's done as a last ditch effort to save the kidney after the patient fails the usual immunosupressants used in AR including IVIG.
Keloids are extremely repsonsive to low dose XRT; however, the US public has an overt fear of XRT compared with European countries. Consequently, the Germans have great data on all kinds of benign diseases, (keloids, plantar fascitis, macular degeneration, histiocytosis X, etc); just look at Strahlentherapie und Onkologie for good articles.