Could A Bump And Itching On Breast Bone Be Due To Change In Thymus Gland?

Im female, 42 years old, I have asthma, have had giant cell reparative granuloma, and recently diagnosed with Myasthenia Gravis. I had a CT scan last year to check for any problems with the Thymus, the results were fine. Recently, a few people have commented on how my breast bone ...has a bump... and for the past two weeks I now have an itch but internal (hard to explain) right at the point where both sides of the ribcage meets the breastbone and immediately below it. Is there any possibility that there could be significant changes in the thymus within a year? is it worth getting it looked at? I dont see this itch in any of the symptoms associated with the thymus.