Graft versus host disease (GVHD) is a common complication of a stem cell/bone marrow transplant. It happens when the donor's immune cells, now in the patient, begin to see the patient's body as foreign, triggering an immune response to attack.
Myelofibrosis is a bone marrow disorder where the marrow is replaced with fibrous scar tissue. It can lead to low blood cell counts and an enlarged spleen. It is considered a myeloproliferative neoplasm (MPN).