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.

Initial symptoms can be nonspecific, particularly in children. Over 50% of children with leukemia had one or more of five features: a liver one can feel (64%), a spleen one can feel (61%), pale complexion (54%), fever (53%), and bruising (52%). Additionally, recurrent infections, feeling tired, arm or leg pain, and enlarged lymph nodes can be prominent features. The B symptoms, such as fever, night sweats, and weight loss, are often present as well.

Central nervous system (CNS) symptoms such cranial neuropathies due to meningeal infiltration are identified in less than 10% of adults and less than 5% of children, particularly mature B-cell ALL (Burkitt leukemia) at presentation.

The signs and symptoms of ALL are variable and include:

- Generalized weakness and feeling tired

- Anemia

- Dizziness

- Headache, vomiting, lethargy, nuchal rigidity, or cranial nerve palsies (CNS involvement)

- Frequent or unexplained fever and infection

- Weight loss and/or loss of appetite

- Excessive and unexplained bruising

- Bone pain, joint pain (caused by the spread of "blast" cells to the surface of the bone or into the joint from the marrow cavity)

- Breathlessness

- Enlarged lymph nodes, liver and/or spleen

- Pitting edema (swelling) in the lower limbs and/or abdomen

- Petechiae, which are tiny red spots or lines in the skin due to low platelet levels

- Testicular enlargement

- Mediastinal mass

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.

Clinically and pathologically, leukemia is subdivided into a variety of large groups. The first division is between its "acute" and "chronic" forms:

- Acute leukemia is characterized by a rapid increase in the number of immature blood cells. The crowding that results from such cells makes the bone marrow unable to produce healthy blood cells. Immediate treatment is required in acute leukemia because of the rapid progression and accumulation of the malignant cells, which then spill over into the bloodstream and spread to other organs of the body. Acute forms of leukemia are the most common forms of leukemia in children.

- Chronic leukemia is characterized by the excessive buildup of relatively mature, but still abnormal, white blood cells. Typically taking months or years to progress, the cells are produced at a much higher rate than normal, resulting in many abnormal white blood cells. Whereas acute leukemia must be treated immediately, chronic forms are sometimes monitored for some time before treatment to ensure maximum effectiveness of therapy. Chronic leukemia mostly occurs in older people, but can occur in any age group.

Additionally, the diseases are subdivided according to which kind of blood cell is affected. This divides leukemias into lymphoblastic or "lymphocytic leukemias" and myeloid or "myelogenous leukemias":

- In lymphoblastic or lymphocytic leukemias, the cancerous change takes place in a type of marrow cell that normally goes on to form lymphocytes, which are infection-fighting immune system cells. Most lymphocytic leukemias involve a specific subtype of lymphocyte, the B cell.

- In myeloid or myelogenous leukemias, the cancerous change takes place in a type of marrow cell that normally goes on to form red blood cells, some other types of white cells, and platelets.

Combining these two classifications provides a total of four main categories. Within each of these main categories, there are typically several subcategories. Finally, some rarer types are usually considered to be outside of this classification scheme.

Acute myeloblastic leukemia is a form of myeloid leukemia affecting myeloblasts.

More specifically, it can refer to:

- Minimally differentiated acute myeloblastic leukemia (M0 in FAB) -

- Acute myeloblastic leukemia without maturation (M1 in FAB) -

- Acute myeloblastic leukemia with maturation (M2 in FAB) -

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.

Acute lymphoblastic leukemia (ALL) is a cancer of the lymphoid line of blood cells characterized by the development of large numbers of immature lymphocytes. Symptoms may include feeling tired, pale skin color, fever, easy bleeding or bruising, enlarged lymph nodes, or bone pain. As an acute leukemia, ALL progresses rapidly and is typically fatal within weeks or months if left untreated.

Most cases occur due to an unknown reason. Genetic risk factors may include Down syndrome, Li-Fraumeni syndrome, or neurofibromatosis type 1. Environment risk factors may include significant radiation exposure or prior chemotherapy. Evidence regarding electromagnetic fields or pesticides is unclear. Some hypothesize that an abnormal immune response to a common infection may be a trigger. The underlying mechanism involves multiple genetic mutations that results in rapid cell division. The excessive immature lymphocytes in the bone marrow interfere with the production of new red blood cells, white blood cells, and platelets. Diagnosis is typically based on blood tests and bone marrow examination.

ALL is typically treated initially with chemotherapy aimed at bringing about remission. This is then followed by further chemotherapy typically over a number of years. Additional treatments may include intrathecal chemotherapy or radiation therapy if spread to the brain has occurred. Stem cell transplantation may be used if the disease recurs following standard treatment. Additional treatments such as immunotherapy are being studied.

ALL affected about 876,000 people globally in 2015 and resulted in about 111,000 deaths. It occurs most commonly in children, particularly those between the ages of two and five. In the United States it is the most common cause of cancer and death from cancer among children. ALL is notable for being the first disseminated cancer to be cured. Survival for children increased from under 10% in the 1960s to 90% in 2015. Survival rates remain lower for babies (50%) and adults (35%).

The most common symptoms of AEL are related to pancytopenia (a shortage of all types of blood cells), including fatigue, infections, and mucocutaneous bleeding. Almost half of people with AEL exhibit weight loss, fever and night sweats at the time of diagnosis. Almost all people with AEL are anemic, and 77% have a hemoglobin level under 10.0 g/dl. Signs of thrombocytopenia are found in about half of people with AEL.

In hairy cell leukemia, the "hairy cells" (malignant B lymphocytes) accumulate in the bone marrow, interfering with the production of normal white blood cells, red blood cells, and platelets. Consequently, patients may develop infections related to low white blood cell count, anemia and fatigue due to a lack of red blood cells, or easy bleeding due to a low platelet count. Leukemic cells may gather in the spleen and cause it to swell; this can have the side effect of making the person feel full even when he or she has not eaten much.

Hairy cell leukemia is commonly diagnosed after a routine blood count shows unexpectedly low numbers of one or more kinds of normal blood cells, or after unexplained bruises or recurrent infections in an otherwise apparently healthy patient.

Platelet function may be somewhat impaired in HCL patients, although this does not appear to have any significant practical effect. It may result in somewhat more mild bruises than would otherwise be expected for a given platelet count or a mildly increased bleeding time for a minor cut. It is likely the result of producing slightly abnormal platelets in the overstressed bone marrow tissue.

Patients with a high tumor burden may also have somewhat reduced levels of cholesterol, especially in patients with an enlarged spleen. Cholesterol levels return to more normal values with successful treatment of HCL.

Myeloid leukemia is a type of leukemia affecting myeloid tissue.

Types include:

- Acute myeloid leukemia

- Chronic myelogenous leukemia

Prognosis is very poor once chronic myelogenous leukemia reaches the accelerated phase; it behaves similarly to acute myeloid leukemia.

BAL has similar symptoms with other types of leukemia, but usually more serious.

Symptoms caused by bone marrow damage

Bruising, spotting: the reason is lack of platelets, it is very common in BAL patients, most of patients die due to the

Anemia: Because the decline of hematopoietic function, need blood transfusion therapy

Persistent fever, infection prolonged healing:

Diffuse hemorrhage: also called Septicemia, which is dangerous and might lead to death.

Symptoms caused by blood cancer cells infiltration into tissues:

Lymphadenopathy

Joint pain

Swelling of the gums

Hepatoslenomegaly

Headache and vomiting: blood cancer infiltration into the wear performance of the central nervous system.

Skin lumps: Because look was slightly green, also known as the "Green tumor."

Pericardial or pleural effusion

Chronic leukemia is an increase of abnormal white blood cells. It differs from acute leukemia, and is categorized as myelogenous or lymphocytic.

Chronic leukemia may refer to:

- Chronic myelogenous leukemia

- Chronic lymphocytic leukemia

- Hairy cell leukemia

"T-cell leukemia" describes several different types of lymphoid leukemias which affect T cells.

The most common T-cell leukemia is precursor T-cell lymphoblastic leukemia. It causes 15% of acute leukemias in childhood, and also 40% of lymphomas in childhood. It is most common in adolescent males. Its morphology is identical to that of "precursor B-cell lymphoblastic leukemia". Cell markers include TdT, CD2, CD7. It often presents as a mediastinal mass because of involvement of the thymus. It is highly associated with NOTCH1 mutations.

Other types include:

- Large granular lymphocytic leukemia

- Adult T-cell leukemia/lymphoma

- T-cell prolymphocytic leukemia

In practice, it can be hard to distinguish T-cell leukemia from T-cell lymphoma, and they are often grouped together.

"B-cell leukemia" describes several different types of lymphoid leukemia which affect B cells.

Other types include (with ICD-O code):

- 9826/3 – Acute lymphoblastic leukemia, mature B-cell type

- 9833/3 – B-cell prolymphocytic leukemia

- 9940/3 – Hairy cell leukemia

Very rarely, chloroma can occur without a known pre-existing or concomitant diagnosis of acute leukemia, acute promyleocytic leukemia or MDS/MPS; this is known as primary chloroma. Diagnosis is particularly challenging in this situation (see below). In almost all reported cases of primary chloroma, acute leukemia has developed shortly afterward (median time to development of acute leukemia 7 months, range 1–25 months). Therefore, primary chloroma could be considered an initial manifestation of acute leukemia, rather than a localized process, and could be treated as such. Where disease development or markers indicate progresses to acute promyleocytic leukemia (AML3) treatment should be tailored to this form of disease.

A specific histochemical reaction, cyanide-resistant peroxidase, permits identification of leukemic blast cells with eosinophilic differentiation and diagnosis of acute eosinoblastic leukemia in some cases of AML with few identifiable eosinophils in blood or marrow.

Most initial symptoms of leukemia are similar to symptoms for irregular bone-marrow function. Typically, most symptoms do not occur during the early stages of leukemia, and children may experience different symptoms. The following are symptoms of leukemia that lead doctors to look for different types of juvenile leukemia:

Monocytic leukemia is a type of myeloid leukemia characterized by a dominance of monocytes in the marrow. When the monocytic cells are predominantly monoblasts, it can be subclassified into acute monoblastic leukemia.

Monocytic leukemia is almost always broken down into "acute" and "chronic":

- acute monocytic leukemia

- chronic myelomonocytic leukemia

Acute leukemia or acute leukaemia is a family of serious medical conditions relating to an original diagnosis of leukemia. In most cases, these can be classified according to the lineage, myeloid or lymphoid, of the malignant cells that grow uncontrolled, but some are mixed and for those such an assignment is not possible.

Forms of acute leukemia include:

- Acute myeloid leukemia

- Acute erythroid leukemia

- Acute lymphoblastic leukemia

- T-cell acute lymphoblastic leukemia

- Adult T-cell leukemia/lymphoma

- (Precursor)T-lymphoblastic leukemia/lymphoma

- "Blast crisis" of chronic myelogenous leukemia

Childhood leukemia is a type of leukemia, usually acute lymphocytic leukemia (ALL), and a type of childhood cancer. The cure rate of childhood leukemia is generally higher than adult leukemia, approaching 90%, although some side effects of treatment last into adulthood. The older aggressive treatments of cranial irradiation and anthracyclines (such as doxorubicin) caused increased risk of solid tumors, heart failure, growth retardation, and cognitive defects.

Leukemia is a hematological malignancy or a cancer of the blood. It develops in the bone marrow, the soft inner part of bones where new blood cells are made. When a child has leukemia, the bone marrow produces white blood cells that do not mature correctly. Normal healthy cells only reproduce when there is enough space for them. The body will regulate the production of cells by sending signals of when to stop production. When a child has leukemia, the cells do not respond to the signals telling them when to stop and when to produce cells, regardless of the available space.

Patients treated with imatinib, dasatinib, and nilotinib have shown meaningful rates of hematologic and cytogenetic response.

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.

People affected by T-cell prolymphocytic leukemia typically have systemic disease at presentation, including enlargement of the liver and spleen, widespread enlargement of the lymph nodes, and skin infiltrates.

Due to the systemic nature of this disease, leukemic cells can be found in peripheral blood, lymph nodes, bone marrow, spleen, liver, and skin. A high lymphocyte count (> 100 x 10/L) along with low amounts of red blood cells and platelets in the blood are common findings. HTLV-1 serologies are negative, and serum immunoglobins are within normal limits with no paraproteins present.

Chloromas may occur in virtually any organ or tissue. The most common areas of involvement are the skin (also known as "leukemia cutis") and the gums. Skin involvement typically appears as violaceous, raised, nontender plaques or nodules, which on biopsy are found to be infiltrated with myeloblasts

Other tissues which can be involved include lymph nodes, the small intestine, the mediastinum, the lung, epidural sites, the uterus, the ovaries, and the orbit of the eye. Symptoms of chloroma at these sites are related to their anatomic location; chloromas may also be asymptomatic and be discovered incidentally in the course of evaluation of a person with acute myeloid leukemia.

Central nervous system involvement, as described above, most often takes the form of "meningeal leukemia", or invasion of the subarachnoid space by leukemic cells. This condition is usually considered separately from chloroma, as it requires different treatment modalities. True chloromas (i.e. solid leukemic tumors) of the central nervous system are exceedingly rare, but has been described.