Chronic neutrophilic leukemia overview

# Overview
Chronic neutrophilic leukemia (CNL) is an extremely rare myeloproliferative neoplasms with almost 200 cases in the world. While, most of the time this disease is asymptomatic, fatigue, weight loss, night sweats, bone pain, gout and pruritus are some of its symptoms. Splenomegaly is found in examination of most patients. CSF3R mutations are seen in most patient and is  responsible for pathogenesis of CNL patients. World health organization (WHO) introduces criteria for the diagnosis of chronic neutrophilic leukemia (CNL) that are based on the laboratory finding of peripheral blood cells, bone marrow, cytogenic mutation, and differential diagnosis. There is no treatment for chronic neutrophilic leukemia (CNL). Although, hematopoitic stem cell transplant, hydroxyurea, interferon, hypomethylating agents, ruxolitinib, thalidomide, cladribine, imatinib, splenic irradiation and splenectomy are some options that are used in patients with CNL. There is no treatment for chronic neutrophilic leukemia (CNL). Although, hematopoitic stem cell transplant, hydroxyurea, interferon, hypomethylating agents, ruxolitinib, thalidomide, cladribine, imatinib, splenic irradiation and splenectomy are some options that are used in patients with CNL.

# Historical Perspective
Chronic neutrophilic leukemia(CNL) was first presented by Tuohy, in a case of splenomegaly and neutrophilic leukocytosis, in 1920. Although, It was named by Tanzer et al, in 1964. WHO introduced the criteria for the diagnosis of this disease as a myeloproliferative disorder in 2001. In 2013, CSF3R (colony stimulating factor 3 receptor) mutations was proposed that was found in the most CNL patients and made a huge change in diagnosis and treatment of this patient.

# Classification
There is no established system for the classification of chronic neutrophilic leukemia (CNL).

# Pathophysiology
The exact pathogenesis of Chronic neutrophilic leukemia (CNL) is not fully understood. Some cytogenic abnormalities like trisomy 7,8,9,21, deletion 11q, 20q6,7  may be seen in CNL patients. The mutation of CSF3R is seen in most patients. Moreover of mutation in CSF3R, there are some other genetic mutations which are less common. Polycythemia vera, plasma cell disorders and nephrotic syndrome can be associated with CNL.

# Causes
The etiology of Chronic neutrophilic leukemia (CNL) is unknown.

# Differentiating Chronic neutrophilic leukemia from Other Diseases
Chronic neutrophilic leukemia (CNL) must be differentiated from other diseases that cause weight loss,  night sweats, hepatosplenomegaly, and palpable lymph nodes and neutrophilia.

# Epidemiology and Demographics
Chronic neutrophilic leukemia is an extremely rare disease. There are almost only 200 patients with CNL worldwide. The exact incidence of CNL is undetermined.
The median age at diagnosis is 66.5 years and the incidence of disease increases with age. There is no racial predilection to CNL and it affects men and women almost equally.

# Risk Factors
Chronic neutrophilic leukemia (CNL) must be differentiated from other diseases that cause weight loss,  night sweats, hepatosplenomegaly, and palpable lymph nodes and neutrophilia.

# Screening
There is insufficient evidence to recommend routine screening for chronic neutrophilic leukemia (CNL).

# Natural History, Complications, and Prognosis
Course of the disease is variable in CNL patients, developing blast crisis is happened in most patients. Moreover, Progression to acute myeloid leukemia may seen in 10-21.2% of patients with CNL. Common complications of CNL include predisposing to hemorrhage, progression of disease, blastic or leukemic conversion and treatment-related toxicity .Prognosis is generally poor, and the 5-year survival rate of patients with CNL is approximately 28%. Some criteria same as treatment resistance, refractory neutrophilia, increasing in red blood cells, platelet transfusion dependency, deterioration of organomegaly and blast crisis indicate disease progression.

# Diagnosis

## Diagnostic Study of Choice
World health organization (WHO) introduces criteria for the diagnosis of chronic neutrophilic leukemia (CNL) that are based on the laboratory finding of peripheral blood cells, bone marrow, cytogenic mutation, and differential diagnosis.

## History and Symptoms
The majority of patients with Chronic neutrophilic leukemia (CNL) are asymptomatic. The most common symptom is fatigue. The other symptoms of CNL include weight loss , night sweats, bone pain, easy bruising, pruritus and gout.

## Physical Examination
The appearance of patient with chronic neutrphilic leukemia (CNL) is usually normal. Common physical examination findings of Chronic neutrophilic leukemia include splenomegaly, hepatomegaly, fever, petechiae, bruises, lymphadenopathy.

## Laboratory Findings
A chronic elevated concentration of blood mature neutrophils is diagnostic for chronic neutrophilic leukemia (CNL). There are other blood, bone marrow and genetic tests which help the diagnosis of CNL.

## Electrocardiogram
There are no ECG findings associated with chronic neutrophilic leukemia (CNL).

## X-ray
There are no x-ray findings associated with chronic neutrophilic leukemia (CNL). However, an x-ray may be helpful in the diagnosis of complications of CNL, which include splenomegaly, hepatomegaly, and lymphadenopathy.

## Echocardiography and Ultrasound
There are no ultrasound findings associated with chronic neutrophilic leukemia (CNL). However, an ultrasoundmay be helpful in the diagnosis of complications of CNL, which include splenomegaly, hepatomegaly, and lymphadenopathy.

## CT scan
TThere are no CT scan findings associated with chronic neutrophilic leukemia (CNL). However, an CT scan may be helpful in the diagnosis of complications of CNL, which include splenomegaly, hepatomegaly, and lymphadenopathy.

## MRI
There are no MRI findings associated with chronic neutrophilic leukemia (CNL). However, an MRI may be helpful in the diagnosis of complications of CNL, which include splenomegaly, hepatomegaly, and lymphadenopathy.

## Other Imaging Findings
There are no other imaging findings associated with chronic neutrophilic leukemia (CNL).

## Other Diagnostic Studies
Bone marrow morphology may be helpful in the diagnosis of chronic neutrophilic leukemia (CNL). Hypercellularity with myeloid hyperplasia, increasing myeloid to erythroid ratio, increasing of myelocytes, metamyelocytes, and bands, absence of basophilia and eosinophilia,Megakaryocytic hyperplasia

# Treatment

## Medical Therapy
There is no standard medical treatment for chronic neutrophilic leukemia (CNL). Although, Hydroxyurea,  Ruxolitinib, Interferon, Thalidomide, Cladribine and Imatinib are some options that are used in patients with CNL.

## Surgery
Splenectomy was used as a palliative treatment in patients of chronic neutrophilic leukemia (CNL) with splenomegaly. Although, because of neutrophilia was became worse in some reports, it's not recommended anymore.

## Interventions
Hematopoitic stem cell transplant is the mainstay of treatment for CNL patients. It is recommended that every patients that are qualified for HSCT, take this treatment. Since, the therapy in blast phases has the poor outcomes, HSCT should be started as soon as possible in the disease course, before blast transformation. Splenic irradiation was used as a palliative treatment in patients of CNL with splenomegaly.

## Primary Prevention
There are no established measures for the primary prevention of chronic neutrophilic leukemia (CNL).

## Secondary Prevention
There are no established measures for the secondary prevention of chronic neutrophilic leukemia (CNL).