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Disease Information

Summary

Primary myelofibrosis is a condition characterized by the buildup of scar tissue (fibrosis) in the bone marrow, the tissue that produces blood cells. Because of the fibrosis, the bone marrow is unable to make enough normal blood cells. The shortage of blood cells causes many of the signs and symptoms of primary myelofibrosis. Initially, most people with primary myelofibrosis have no signs or symptoms. Eventually, fibrosis can lead to a reduction in the number of red blood cells, white blood cells, and platelets. A shortage of red blood cells (anemia) often causes extreme tiredness (fatigue) or shortness of breath. A loss of white blood cells can lead to an increased number of infections, and a reduction of platelets can cause easy bleeding or bruising. Because blood cell formation (hematopoiesis) in the bone marrow is disrupted, other organs such as the spleen or liver may begin to produce blood cells. This process, called extramedullary hematopoiesis, often leads to an enlarged spleen (splenomegaly) or an enlarged liver (hepatomegaly). People with splenomegaly may feel pain or fullness in the abdomen, especially below the ribs on the left side. Other common signs and symptoms of primary myelofibrosis include fever, night sweats, and bone pain. Primary myelofibrosis is most commonly diagnosed in people aged 50 to 80 but can occur at any age.

About Primary myelofibrosis

Many rare diseases have limited information. Currently, GARD aims to provide the following information for this disease:

  • Symptoms:May start to appear as an Adult.
  • Cause:GARD does not currently have information about the cause of this disease.
  • Organizations:Patient organizations dedicated to this rare disease are available on GARD, or you may contact a GARD Information Specialist for additional information.
  • Categories: Cancer(Cancer is a disease in which some of the body's cells grow uncontrollably and can spread to other parts of the body.)Blood diseases(Blood diseases affect the blood or blood-forming organs, including red blood cells, white blood cells, platelets, plasma, and bone marrow.)

Resource(s) for Medical Professionals and Scientists on This Disease:

  • MONDO provides GARD with information for this disease.
  • Orphanet provides GARD with information for this disease.
  • RARe-SOURCE™ offers rare disease gene variant annotations and links to rare disease gene literature.

Resource(s) for Medical Professionals and Scientists on This Disease:

  • MONDO provides GARD with information for this disease.
  • Orphanet provides GARD with information for this disease.
  • RARe-SOURCE™ offers rare disease gene variant annotations and links to rare disease gene literature.

About Primary myelofibrosis

Many rare diseases have limited information. Currently, GARD aims to provide the following information for this disease:

  • Symptoms:May start to appear as an Adult.
  • Cause:GARD does not currently have information about the cause of this disease.
  • Organizations:Patient organizations dedicated to this rare disease are available on GARD, or you may contact a GARD Information Specialist for additional information.
  • Categories: Cancer(Cancer is a disease in which some of the body's cells grow uncontrollably and can spread to other parts of the body.)Blood diseases(Blood diseases affect the blood or blood-forming organs, including red blood cells, white blood cells, platelets, plasma, and bone marrow.)

When Do Symptoms of Primary myelofibrosis Begin?

Symptoms of this disease may start to appear as an Adult.

The age symptoms may begin to appear differs between diseases. Symptoms may begin in a single age range, or during several age ranges. The symptoms of some diseases may begin at any age. Knowing when symptoms may have appeared can help medical providers find the correct diagnosis.
  1. Prenatal
    Before Birth
  2. Newborn
    Birth-4 weeks
  3. Infant
    1-23 months
  4. Child
    2-11 years
  5. Adolescent
    12-18 years
  6. Adult Selected
    19-65 years
  7. Older Adult
    65+ years
Symptoms may start to appear as an Adult.
This information comes from Orphanet

Symptoms

You may have one or more symptoms, and they may be mild or severe. Having some or all of these symptoms does not mean you have this disease. Only a health care provider can diagnose you.

Common

Many people have these, but not everyone.

  • Abnormal bone marrow cell morphology
  • Abnormal megakaryocyte morphology
  • Abnormality of blood and blood-forming tissues
  • Constitutional symptom
  • Enlarged liver (Hepatomegaly)
  • Enlarged liver and spleen (Hepatosplenomegaly)
  • Fatigue
  • Increased spleen size (Splenomegaly)
  • Low number of red blood cells or hemoglobin (Anemia)
  • Low platelet count (Thrombocytopenia)
  • Pallor

Uncommon

Some people have these, but most people do not.

  • Abnormal blood clot (Abnormal thrombosis)
  • Anorexia
  • Bleeding tendency (Abnormal bleeding)
  • Blood clot in artery (Arterial thrombosis)
  • Blood clot in vein (Venous thrombosis)
  • Bone marrow hypercellularity
  • Easy fatigability
  • Ecchymosis
  • Elevated white blood count (Increased total leukocyte count)
  • Extramedullary hematopoiesis
  • Fever
  • Flank pain
  • Hematological neoplasm
  • Increased number of platelets in blood (Thrombocytosis)
  • Low blood cell count (Pancytopenia)
  • Low-grade fever
  • Petechiae
  • Poikilocytosis
  • Portal hypertension
  • Red or purple spots on the skin (Purpura)
  • Strawberry mark (Hemangioma)
  • Swollen lymph nodes (Lymphadenopathy)
  • Wasting syndrome (Cachexia)
This information comes from the Human Phenotype Ontology (HPO)

Navigating Health Care Decisions

On average, it can take more than six years to receive an accurate diagnosis. Many primary care providers (PCPs) may not be familiar with rare diseases, and patients often need to visit multiple specialists or seek second opinions to get answers.

If a diagnosis remains unclear, visiting a multidisciplinary care center or university hospital may help. These centers bring together teams of specialists who can work together to evaluate symptoms and coordinate a diagnosis. This team-based approach is also helpful after a diagnosis, when managing care for rare diseases.

Because only about 5% of rare diseases have FDA-approved treatments, finding the right healthcare team to manage your symptoms and overall health is essential. People living with rare diseases often face challenges such as delayed diagnosis, limited treatment options, and difficulty accessing knowledgeable providers. Building a care team that understands your needs can make a significant difference in your quality of life.

Your Health Care Team

Why is building the right health care team important?

Building the right health care team is key to the diagnosis, treatment, and management of your long-term health journey living with a rare disease. Start by choosing a primary care provider (PCP). Your PCP will be your main point of contact and help coordinate care with other medical professionals. Your PCP may order tests or refer you to specialists. To find a PCP near you, use the Medicare provider search tool and enter your location and “Primary Care Provider.”

Seeing multiple specialists is important for people with rare diseases because these conditions often affect many parts of the body and require care from doctors with different expertise. Most primary care providers may not be familiar with rare diseases, so involving specialists can lead to a more accurate diagnosis and better care. A coordinated team approach ensures that all symptoms are addressed and that care is well-managed. It can also connect patients with the latest research or treatment options.

These specialists may help in the diagnosis, management, and treatment of Primary myelofibrosis:

Hematologists are doctors with specialized training in diagnosing and treating diseases that affect the blood and bone marrow, where blood cells are produced. They also manage certain conditions of the lymphatic system, which includes the spleen and lymph tissues. Hematologists commonly care for people with anemia, bleeding or clotting disorders, and blood cancers such as leukemia and lymphoma. To diagnose these conditions, they may order blood tests or perform bone marrow biopsies.

You may want to consider bringing a copy of your medical history and a list of any medications to your appointment.

Ask your primary care provider for a referral or use this directory provided by the American Society of Hematology to find a specialist.
Oncologists are doctors with specialized training in diagnosing, treating, and managing different types of cancer and conditions that could become cancerous. They may specialize in specific cancer types, such as blood cancers, breast cancer, or gastrointestinal cancers. Some oncologists also have training in rare or inherited cancers. They use a range of treatments, including surgery, chemotherapy, radiation therapy, immunotherapy, and targeted drug therapies.

You may want to consider bringing a copy of your medical history and a list of any medications to your appointment.

Ask your primary care provider for a referral or use this directory by Medicare to search for an oncologist in your area. Search using the keywords “Medical Oncology.”

Multidisciplinary Care Centers

Is It Time to Get a Second Opinion or Specialized Evaluation?

If you've visited your PCP, met with specialists, and undergone the recommended tests, but are still searching for a diagnosis, it may be time to visit an academic medical center or, for pediatric patients, a children's hospital. Academic medical centers and children's hospitals, often called multidisciplinary care centers, typically bring together specialists from different fields to work together on complex cases like rare diseases.

Multidisciplinary care centers may offer more coordinated care and be involved in clinical research, which may help reduce the time to diagnosis and provide access to emerging diagnostic tools. Specialists at these centers may have a deeper understanding of rare diseases and serve as a resource when you'd like a second opinion, particularly when test results or treatment plans are not delivering expected results.

Find hospitals that may partner with medical schools and programs in your area. 

Rare Disease Experts

How can you find a rare disease expert?

If a diagnosis, care management, or treatment plan remains unclear despite extensive efforts by your PCP and specialists, it may be time to find a rare disease expert for your disease, if available. A rare disease expert is a medical provider that has knowledge or training on specific rare disease(s), but there may only be a few experts in your state, region, or country. Rare disease experts may work at large research or teaching hospitals, sometimes called centers of excellence. Centers of Excellence commit to sharing knowledge and best practices that can lead to improved care and treatment for individuals living with a rare disease. 

You can also contact a GARD Information Specialist for help finding experts, centers of excellence, or clinics that focus on your disease.
You can ask your care providers for help finding an expert or use directory tools to search for experts near you. The following organization(s) may maintain a list of experts or expert centers for people living with Primary myelofibrosis:

Find Your Community

How can patient organizations help?

Patient organizations can help patients and families connect. They build public awareness of the disease and are a driving force behind research to improve patients' lives. They may offer online and in-person resources to help people live well with their disease. Many collaborate with medical experts and researchers.

Services of patient organizations differ, but may include:

  • Ways to connect to others and share personal stories
  • Easy-to-read information
  • Up-to-date treatment and research information
  • Patient registries
  • Lists of specialists or specialty centers
  • Financial aid and travel resources


Please note: GARD provides organizations for informational purposes only and not as an endorsement of their services. Contact a GARD Information Specialist for more information on organizations that may be dedicated to this disease. Please contact an organization directly if you have questions about the information or resources it provides.


View GARD's criteria for including patient organizations, which can be found under the FAQs on our About GARD page. Request an update or to have your organization added to GARD. 

Patient Organizations

4 Organizations

Aplastic Anemia and MDS International Foundation

People With

Primary myelofibrosis

Helpful Links
Country

United States

MPN Research Foundation

People With

Primary myelofibrosis

Country

United States

Blood Cancer United

People With

Blood or bone marrow disease

Country

United States

HealthTree Foundation

People With

Blood or bone marrow disease

Country

United States

OrganizationPeople WithHelpful LinksCountry
Aplastic Anemia and MDS International FoundationPrimary myelofibrosisList of Experts
Research Registry		United States
MPN Research FoundationPrimary myelofibrosisUnited States
Blood Cancer UnitedBlood or bone marrow diseaseUnited States
HealthTree FoundationBlood or bone marrow diseaseUnited States

Participate in Research

Clinical studies are a part of clinical research and play an important role in medical advances for rare diseases. Through clinical studies, researchers may ultimately uncover better ways to treat, prevent, diagnose, and understand human diseases.

What Are Clinical Studies?

Clinical studies are medical research involving people as participants. There are two main types of clinical studies:

  1. Clinical trials determine if a new test or treatment for a disease is effective and safe by comparing groups receiving different tests/treatments.
  2. Observational studies involve recording changes over time among a specific group of people in their natural settings.

Learn more about clinical trials from this National Institutes of Health webpage.

Why Participate in Clinical Studies?

People participate in clinical trials for many reasons. People with a disease may participate to receive the newest possible treatment and additional care from clinical study staff as well as to help others living with the same or a similar disease. Healthy volunteers may participate to help others and to contribute to moving science forward.

To find the right clinical study we recommend you consult your doctors, other trusted medical professionals, and patient organizations. Additionally, you can use ClinicalTrials.gov to search for clinical studies by disease, terms, or location.

What if There Are No Available Clinical Studies?

ResearchMatch helps connect people interested in research studies  with researchers from top medical centers across the United States. Anyone from the U.S. can register with this free program funded by NIH. Researchers from participating institutions use the database to search for and invite patients or healthy volunteers who meet their study criteria to participate.

Why may you want to consider joining the All of Us Research Program?

The All of Us Research Program is inviting 1 million people from all backgrounds across the U.S. to help build one of the most diverse health databases in history. Researchers will use the data to learn how our biology, lifestyle, and environment affect health. This may one day help them find ways to treat and prevent diseases.

ClinicalTrials.gov, an affiliate of NIH, provides current information on clinical research studies in the United States and abroad. Talk to a trusted doctor before choosing to participate in any clinical study. We recommend checking this site often and searching for studies with related terms/synonyms to improve results.
Search ClinicalTrials.gov for this disease.
GARDGenetic and Rare Diseases
Information Center
Contact a GARD Information Specialist if you need help finding more information on this rare disease or available clinical studies. Please note that GARD cannot enroll individuals in clinical studies.
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Sources & References

Last Updated: September 2026