The primary sign of myelofibrosis is reactive bone marrow fibrosis, but it is often accompanied by:

- Abdominal fullness related to an enlarged spleen (splenomegaly).

- Bone pain

- Bruising and easy bleeding due to inadequate numbers of platelets

- Cachexia (loss of appetite, weight loss, and fatigue)

- Enlargement of both the liver and spleen

- Fatigue

- Gout and high uric acid levels

- Increased susceptibility to infection, such as pneumonia

- Pallor and shortness of breath due to anemia

- In rarer cases, a raised red blood cell volume

- Cutaneous myelofibrosis is a rare skin condition characterized by dermal and subcutaneous nodules.

Myelofibrosis, also known as osteomyelofibrosis, is a relatively rare bone marrow cancer. It is currently classified as a myeloproliferative neoplasm, in which the proliferation of an abnormal clone of hematopoietic stem cells in the bone marrow and other sites results in fibrosis, or the replacement of the marrow with scar tissue.

The term "myelofibrosis" alone usually refers to primary myelofibrosis (PMF), also known as chronic idiopathic myelofibrosis (cIMF); the terms idiopathic and primary mean that in these cases the disease is of unknown or spontaneous origin. This is in contrast with myelofibrosis that develops secondary to polycythemia vera or essential thrombocythaemia. Myelofibrosis is a form of myeloid metaplasia, which refers to a change in cell type in the blood-forming tissue of the bone marrow, and often the two terms are used synonymously. The terms agnogenic myeloid metaplasia and myelofibrosis with myeloid metaplasia (MMM) are also used to refer to primary myelofibrosis.

Bone marrow biopsy shows abnormal megakaryocytes, macrocytic erythropoiesis, and defects in neutrophil production and fibrosis of the marrow (myelofibrosis).

Clinically patients present with reduction in the count of all blood cells (pancytopenia), a very few blasts in the peripheral blood and no or little spleen enlargement (splenomegaly).

Cells are usually CD34 positive.

Myelophthisic anemia (or myelophthisis) is a severe type of anemia found in some people with diseases that affect the bone marrow. Myelophthisis refers to the displacement of hemopoietic bone-marrow tissue either by fibrosis, tumors or granulomas. The word comes from the roots "myelo-", which refers to bone marrow, and "phthysis", shrinkage or atrophy.

Myelophthisis can occur in the setting of chronic myeloproliferative disease (e.g. myelofibrosis), leukemia, lymphoma, and metastatic carcinoma or myeloma. It is common in people who have chronic idiopathic myelofibrosis. It has been linked to small-cell lung cancer, breast cancer or prostate cancer that metastasizes to the bone marrow.

Historically, the most common cause of displacement of healthy bone marrow was tuberculosis.

Currently, the most common cause is displacement of bone marrow by metastatic cancer (extramedullary hematopoiesis tends to be modest). Other causes include myeloproliferative disorders (especially late-stage or spent polycythemia vera), granulomatous diseases, and (lipid) storage diseases. Myelofibrosis can occur in all of these.

Factors that may contribute to decreased RBC production include a decreased quantity of functioning hematopoietic tissue, disordered metabolism related to the underlying disorder, and, in some cases, erythrophagocytosis.

Acute panmyelosis with myelofibrosis (APMF) it is a poorly defined disorder that arises as either a clonal disorder, or following toxic exposure to the bone marrow.

The most common clinical finding is hepatosplenomegaly. Pruritus, gout, and mucocutaneous bleeding are occasionally seen.

Refractory cytopenia of childhood (RCC) is a subgroup of myelodysplastic syndrome (MDS), having been added to the World Health Organization classification in 2008. Before then, RCC cases were classified as childhood aplastic anemia. RCC is the most common form of MDS in children and adolescents, accounting for approximately half of all MDS cases.

Although not a malignant neoplasm like other cancers, MPNs are classified within the hematological neoplasms. There are four main myeloproliferative diseases, which can be further categorized by the presence of the Philadelphia chromosome:

In 2008, the World Health Organization listed these diagnoses as types of MPD:

- Chronic myelogenous leukemia (BCR-ABL1–positive)

- Chronic neutrophilic leukemia

- Polycythemia vera

- Primary myelofibrosis

- Essential thrombocythemia

- Chronic eosinophilic leukemia (not otherwise specified)

- Mastocytosis

One of the most common signs of CMML is splenomegaly, found in approximately half of cases. Other less frequent signs and symptoms consist of anaemia, fever, weight loss, night sweats, infection, bleeding, synovitis, lymphadenopathy, skin rashes, pleural effusion, pericardial effusion and peritoneal effusion.

Chronic myelomonocytic leukaemia (CMML) is a type of leukaemia, which are cancers of the blood-forming cells of the bone marrow. In adults, blood cells are formed in the bone marrow, by a process that is known as haematopoiesis. In CMML, there are increased numbers of monocytes and immature blood cells (blasts) in the peripheral blood and bone marrow, as well as abnormal looking cells (dysplasia) in at least one type of blood cell.

CMML shows characteristics of a myelodysplastic syndrome (MDS); a disorder that produces abnormal looking blood cells, and a myeloproliferative disorder (MPD); a disorder characterised by the overproduction of blood cells. For this reason CMML was reclassified as a MDS/MPN overlap disorder in 2002. For a diagnosis of CMML, the World Health Organisation (WHO) states that the blood monocyte count must be >1x10/L, no Philadelphia chromosome or mutations in the PDGFRA or PDGFRB gene should be present, the blast count must be <20% and dysplasia of at least one lineage of myeloid blood cell should be present.

Azacitidine is a drug used to treat CMML and is approved by the Food and Drug Administration (FDA) and the European Medicines Agency. Stem cell transplant is also used to treat CMML, and involves the transplantation of donor haematopoietic stem cells into the recipient. Blood transfusion and erythropoietin are used to treat disease associated anaemia.

Acute megakaryoblastic leukemia (AMKL) is a form of leukemia where a majority of the blasts are megakaryoblastic.

It is classified under AML-M7 category of the French-American-British classification.

The latest WHO classification (2008, Lyon), classifies Acute Myeloid Leukemia into distinct subtypes, based on clinico-pathological and molecular features. Acute megakaryoblastic leukemia is placed under the AML-Not Otherwise Specified subcategory.

Diagnosis requires more than 20% Blasts in the marrow/ peripheral blood with more than 50% demonstrating megakaryocytic derivation by morphology, immunophenotypic or electron microscopic studies.

Most signs and symptoms of AML are caused by the replacement of normal blood cells with leukemic cells. A lack of normal white blood cell production makes people more susceptible to infections; while the leukemic cells themselves are derived from white blood cell precursors, they have no infection-fighting capacity. A drop in red blood cell count (anemia) can cause fatigue, paleness, and shortness of breath. A lack of platelets can lead to easy bruising or bleeding with minor trauma.

The early signs of AML are often vague and nonspecific, and may be similar to those of influenza or other common illnesses. Some generalized symptoms include fever, fatigue, weight loss or loss of appetite, shortness of breath, anemia, easy bruising or bleeding, petechiae (flat, pin-head sized spots under the skin caused by bleeding), bone and joint pain, and persistent or frequent infections.

Enlargement of the spleen may occur in AML, but it is typically mild and asymptomatic. Lymph node swelling is rare in AML, in contrast to acute lymphoblastic leukemia. The skin is involved about 10% of the time in the form of leukemia cutis. Rarely, Sweet's syndrome, a paraneoplastic inflammation of the skin, can occur with AML.

Some people with AML may experience swelling of the gums because of infiltration of leukemic cells into the gum tissue. Rarely, the first sign of leukemia may be the development of a solid leukemic mass or tumor outside of the bone marrow, called a chloroma. Occasionally, a person may show no symptoms, and the leukemia may be discovered incidentally during a routine blood test.

The myeloproliferative neoplasms (MPNs), previously myeloproliferative diseases (MPDs), are a group of diseases of the bone marrow in which excess cells are produced. They are related to, and may evolve into, myelodysplastic syndrome and acute myeloid leukemia, although the myeloproliferative diseases on the whole have a much better prognosis than these conditions. The concept of myeloproliferative disease was first proposed in 1951 by the hematologist William Dameshek. In the most recent World Health Organization classification of hematologic malignancies, this group of diseases was renamed from "myeloproliferative diseases" to "myeloproliferative neoplasms". This reflects the underlying clonal genetic changes that are a salient feature of this group of disease.

The increased numbers of blood cells may not cause any symptoms, but a number of medical problems or symptoms may occur. The risk of thrombosis is increased in some types of MPN.

Symptoms result from underproduction of red blood cells (weakness, pallor, failure to thrive, pica), white blood cells (recurrent or overwhelming infection), and/or platelets (bleeding).

Bone marrow transplant is the only known curative treatment.

Signs and symptoms are nonspecific and generally related to the blood cytopenias:

- Anemia (low RBC count or reduced hemoglobin) —chronic tiredness, shortness of breath, chilled sensation, sometimes chest pain

- Neutropenia (low neutrophil count) — increased susceptibility to infection

- Thrombocytopenia (low platelet count) — increased susceptibility to bleeding and ecchymosis (bruising), as well as subcutaneous hemorrhaging resulting in purpura or petechiae

Many individuals are asymptomatic, and blood cytopenia or other problems are identified as a part of a routine blood count:

- Neutropenia, anemia, and thrombocytopenia

- Splenomegaly or rarely hepatomegaly

- Abnormal granules in cells, abnormal nuclear shape and size

- Chromosome abnormality, including chromosomal translocations and abnormal chromosome number

Although some risk exists for developing acute myelogenous leukemia, about 50% of deaths occur as a result of bleeding or infection. However, leukemia that occurs as a result of myelodysplasia is notoriously resistant to treatment.

Anemia dominates the early course. Most symptomatic patients complain of the gradual onset of fatigue and weakness, dyspnea, and pallor, but at least half the patients are asymptomatic and their MDS is discovered only incidentally on routine blood counts. Previous chemotherapy or radiation exposure is an important fact in the person's medical history. Fever and weight loss should point to a myeloproliferative rather than myelodysplastic process.

The following symptoms are typical ones which lead to testing for JMML, though children with JMML may exhibit any combination of them: pallor, fever, infection, bleeding, cough, poor weight gain, a maculopapular rash (discolored but not raised, or small and raised but not containing pus), lymphadenopathy (enlarged lymph nodes), moderate hepatomegaly (enlarged liver), marked splenomegaly (enlarged spleen), leukocytosis (high white blood cell count in blood), absolute monocytosis (high monocyte count in blood), anemia (low red blood cell count in blood), and thrombocytopenia (low platelet count in blood). Most of these conditions are common, nonspecific signs and symptoms.

Children with JMML and neurofibromatosis 1 (NF1) (about 14% of children with JMML are also clinically diagnosed with NF1, though up to 30% carry the NF1 gene mutation) may also exhibit any of the following symptoms associated with NF1 (in general, only young children with NF1 are at an increased risk of developing JMML):

- 6 or more café-au-lait (flat, coffee-colored) spots on the skin

- 2 or more neurofibromas (pea-size bumps that are noncancerous tumors) on or under the skin

- Plexiform neurofibromas (larger areas on skin that appear swollen)

- Optic glioma (a tumor on the optic nerve that affects vision)

- Freckles under the arms or in the groin

- 2 or more Lisch nodules (tiny tan or brown-colored spots on the iris of the eye)

- Various bone deformations including bowing of the legs below the knee, scoliosis, or thinning of the shin bone

Noonan syndrome (NS) may predispose to the development of JMML or a myeloproliferative disorder (MPD) associated with NS (MPD/NS) which resembles JMML in the first weeks of life. However, MPD/NS may resolve without treatment. Children with JMML and Noonan's syndrome may also exhibit any of the following most-common symptoms associated with Noonan's syndrome:

- Congenital heart defects, in particular, pulmonic stenosis (a narrowing of the valve from the heart to the lungs)

- Undescended testicles in males

- Excess skin and low hair line on back of neck

- Widely set eyes

- Diamond-shaped eyebrows

- Ears that are low-set, backward-rotated, thick outer rim

- Deeply grooved philtrum (upper lip line)

- Learning delays

The most common symptoms in children are easy bruising, pale skin, fever, and an enlarged spleen or liver.

Damage to the bone marrow, by way of displacing the normal bone marrow cells with higher numbers of immature white blood cells, results in a lack of blood platelets, which are important in the blood clotting process. This means people with leukemia may easily become bruised, bleed excessively, or develop pinprick bleeds (petechiae).

White blood cells, which are involved in fighting pathogens, may be suppressed or dysfunctional. This could cause the patient's immune system to be unable to fight off a simple infection or to start attacking other body cells. Because leukemia prevents the immune system from working normally, some patients experience frequent infection, ranging from infected tonsils, sores in the mouth, or diarrhea to life-threatening pneumonia or opportunistic infections.

Finally, the red blood cell deficiency leads to anemia, which may cause dyspnea and .

Some patients experience other symptoms, such as feeling sick, having fevers, chills, night sweats, feeling fatigued and other flu-like symptoms. Some patients experience nausea or a feeling of fullness due to an enlarged liver and spleen; this can result in unintentional weight loss. Blasts affected by the disease may come together and become swollen in the liver or in the lymph nodes causing pain and leading to nausea.

If the leukemic cells invade the central nervous system, then neurological symptoms (notably headaches) can occur. Uncommon neurological symptoms like migraines, seizures, or coma can occur as a result of brain stem pressure. All symptoms associated with leukemia can be attributed to other diseases. Consequently, leukemia is always diagnosed through medical tests.

The word "leukemia", which means 'white blood', is derived from the characteristic high white blood cell count that presents in most afflicted patients before treatment. The high number of white blood cells are apparent when a blood sample is viewed under a microscope, with the extra white blood cells frequently being immature or dysfunctional. The excessive number of cells can also interfere with the level of other cells, causing further harmful imbalance in the blood count.

Some leukemia patients do not have high white blood cell counts visible during a regular blood count. This less-common condition is called "aleukemia". The bone marrow still contains cancerous white blood cells which disrupt the normal production of blood cells, but they remain in the marrow instead of entering the bloodstream, where they would be visible in a blood test. For an aleukemic patient, the white blood cell counts in the bloodstream can be normal or low. Aleukemia can occur in any of the four major types of leukemia, and is particularly common in hairy cell leukemia.

Refractory anemia with ring sideroblasts (RARS) is a type of myelodysplastic syndrome. RARS is characterized by 5% or less myeloblasts in bone marrow. RARS is distinguished from refractory anemia by having 15% or more ringed sideroblasts among the erythroid precursors in the bone marrow.

Chronic neutrophilic leukemia (CNL) is a rare myeloproliferative neoplasm that features a persistent neutrophilia in peripheral blood, myeloid hyperplasia in bone marrow, hepatosplenomegaly, and the absence of the Philadelphia chromosome or a BCR/ABL fusion gene.

The disease in the lungs is characterized by enlargement of the tracheobronchial lymph nodes and infiltration of the lungs, sometimes leading to lung lobe consolidation and pleural effusion. Signs and symptoms include cough, loss of appetite, weight loss, anemia, and difficulty breathing. Seizures and rear limb weakness can be seen. Invasion of the bone marrow can cause pancytopenia. Diagnosis requires a biopsy.

Myelodysplastic syndromes (MDS) are a group of cancers in which immature blood cells in the bone marrow do not mature and therefore do not become healthy blood cells. Early on there are typically no symptoms. Later symptoms may include feeling tired, shortness of breath, easy bleeding, or frequent infections. Some types may develop into acute myeloid leukemia.

Risk factors include previous chemotherapy or radiation therapy, exposure to certain chemicals such as tobacco smoke, pesticides, and benzene, and exposure to heavy metals such as mercury or lead. Problems with blood cell formation result in some combination of low red blood cells, low platelets, and low white blood cells. Some types have an increase in immature blood cells, called blasts, in the bone marrow or blood. The types of MDS are based on specific changes in the blood cells and bone marrow.

Treatments may include supportive care, drug therapy, and stem cell transplantation. Supportive care may include blood transfusions, medications to increase the making of red blood cells, and antibiotics. Drug therapy may include the medication lenalidomide, antithymocyte globulin, and azacitidine. Certain people can be cured with chemotherapy followed by a stem-cell transplant from a donor.

About seven per 100,000 people are affected with about four per 100,000 people newly acquiring the condition each year. The typical age of onset is 70 years. The outlook depends on the type of cells affected, the number of blasts in the bone marrow or blood, and the changes present in the chromosomes of the affected cells. The typical survival rate following diagnosis is 2.5 years. The conditions were first recognized in the early 1900s. The current name came into use in 1976.

The way CML presents depends on the stage of the disease at diagnosis as it has been known to skip stages in some cases.

Most patients (~90%) are diagnosed during the chronic stage which is most often asymptomatic. In these cases it may be diagnosed incidentally with an elevated white blood cell count on a routine laboratory test. It can also present with symptoms indicative of hepatosplenomegaly and the resulting upper quadrant pain this causes. The enlarged spleen may put pressure on the stomach causing a loss of appetite and resulting weight loss. It may also present with mild fever and night sweats due to an elevated basal level of metabolism.

Some (<10%) are diagnosed during the accelerated stage which most often presents bleeding, petechiae and ecchymosis. In these patients fevers are most commonly the result of opportunistic infections.

Some patients are initially diagnosed in the blast phase in which the symptoms are most likely fever, bone pain and an increase in bone marrow fibrosis.

Acute mast cell leukemia is a rapidly progressive disorder with leukemic mast cells in blood and in large numbers in marrow. The common signs and symptoms include fever, headache, flushing of face and trunk. The typical cutaneous mast cell infiltrates of urticaria pigmentosa are usually not present before, during, or after diagnosis in patients who have mast cell leukemia. Symptoms include abdominal pain, bone pain, and peptic ulcer which are more prevalent than in other subtypes of acute myeloid leukemia. These former symptoms are due to release of a substance called histamine from neoplastic mast cells. Enlargement of the liver and spleen, or hepatosplenomegaly is characteristic. The mast cells release also many anticoagulants like heparin which can lead to serious bleeding. Liver and splenic dysfunction also contributes to hemorrhage. Involvement of the bone can lead to osteoporosis. Abdominal ultrasound or computerized tomography (CT) scanning is used to look for hepatosplenomegaly and lymphadenopathy. Plain radiography and bone densitometry can be used to assess bone involvement and the presence of osteoporosis. Endoscopy and biopsy can be useful if gut involvement is suspected.

Acute myeloid leukemia (AML) is a cancer of the myeloid line of blood cells, characterized by the rapid growth of abnormal cells that build up in the bone marrow and blood and interfere with normal blood cells. Symptoms may include feeling tired, shortness of breath, easy bruising and bleeding, and increased risk of infection. Occasionally spread may occur to the brain, skin, or gums. As an acute leukemia, AML progresses rapidly and is typically fatal within weeks or months if left untreated.

Risk factors include smoking, previous chemotherapy or radiation therapy, myelodysplastic syndrome, and exposure to the chemical benzene. The underlying mechanism involves replacement of normal bone marrow with leukemia cells, which results in a drop in red blood cells, platelets, and normal white blood cells. Diagnosis is generally based on bone marrow aspiration and specific blood tests. AML has several subtypes; for which treatments and outcomes may vary.

AML is typically initially treated with chemotherapy aimed at inducing remission. People may than go on to receive additional chemotherapy, radiation therapy, or a stem cell transplant. The specific genetic mutations present within the cancer cells may guide therapy, as well as determine how long that person is likely to survive. Arsenic trioxide may be tried in cases that have recurred following usual treatments.

AML affected about one million people globally in 2015 and resulted in 147,000 deaths. It most commonly occurs in older adults. Males are affected more often than females. AML is curable in about 35% of people under 60 years old and 10% over 60 years old. Older people who are not healthy enough to receive intensive chemotherapy have a typical survival of 5–10 months. It accounts for roughly 1.8% of cancer deaths in the United States.