Overview

Myelofibrosis is an uncommon type of bone marrow cancer that disrupts your body's normal production of blood cells.

Myelofibrosis causes extensive scarring in your bone marrow, leading to severe anemia that can cause weakness and fatigue. Bone marrow scarring can also cause you to have a low number of blood-clotting cells called platelets, which increases the risk of bleeding. Myelofibrosis often causes an enlarged spleen.

Myelofibrosis is considered to be a chronic leukemia — a cancer that affects the blood-forming tissues in the body. Myelofibrosis belongs to a group of diseases called myeloproliferative disorders.

Myelofibrosis can happen on its own (primary myelofibrosis) or it can develop from another bone marrow disorder (secondary myelofibrosis).

Some people with myelofibrosis have no symptoms and might not need treatment right away. Others with more-serious forms of the disease might need aggressive treatments right away. Treatment for myelofibrosis, which focuses on relieving symptoms, can involve a variety of options.