I do have MG, did not have a thymoma, but did have an enlarged (hyperplastic) thymus. (9 cm by 11cm) I definitely did feel pain, about 1 1/2 " to the left of my sternum, 1" below my collarbone. It felt like a rock was pushing against the bone from the inside. More of an ache than a sharp pain. Never felt that same pain again after my thymectomy.