Myelodysplastic syndrome overview

# Overview
The myelodysplastic syndromes was first described in 1900 by Leube. Myelodysplastic syndromes may be classified into several subtypes based on the French-American-British (FAB) classification and the World Health Organization (WHO) classification methods. Cytogenetic abnormalities involved in the pathogenesis of myelodysplastic syndrome include isolated deletion of 5q, monosomy 7, and monosomy 8. Myelodysplastic syndrome is associated with Fanconi syndrome, Diamond-Blackfan anemia, Shwachman-Diamond syndrome. There are no characteristic findings of myelodysplastic syndrome on gross pathology. On microscopic histopathological analysis, dyserythropoiesis, dysgranulopoiesis, and dysmegakaryocytopoiesis are findings of myelodysplastic syndrome. There are no known direct causes for primary myelodysplastic syndrome. Common risk factors for secondary myelodysplastic syndrome can be found here. Myelodysplastic syndrome must be differentiated from other diseases that cause anemia, neutropenia, and thrombocytopenia, such as: aplastic anemia, fanconi anemia, pure red cell aplasia, Shwachman-Diamond syndrome, paroxysmal nocturnal hemoglobinuria, parovirus B19 infection, and vitamin B12 defeciency. The incidence of myelodysplastic syndrome is approximately 4.4 to 4.6 cases per 100,000 individuals in the United States. Myelodysplastic syndrome commonly affects older patients. Males are more commonly affected with myelodysplastic syndrome than females. Myelodysplastic syndrome usually affects individuals of the Caucasian race. Common risk factors in the development of myelodysplastic syndrome are past treatment with chemotherapy, radiation therapy, past exposure to tobacco smoke, ionizing radiation, organic chemicals, and heavy metals. If left untreated, a high percentage of patients with myelodysplastic syndrome may progress to develop acute myeloid leukemia or die due to bone marrow failure. Common complications of myelodysplasia include progression to acute myeloid leukemia, bone marrow failure, infection, hemorrhage, and iron overload. Prognosis is generally poor, and the 5-year survival rate of patients with high IPSS score myelodysplastic syndrome is approximately 55%. Symptoms of myelodysplastic syndrome include bleeding, easy bruising, shortness of breath, weakness, and fatigue. Common physical examination findings of myelodysplastic syndrome include pallor, hepatomegaly, splenomegaly, lymphadenopathy, fever, and petechiae. Laboratory findings consistent with the diagnosis of myelodysplastic syndrome include abnormal complete blood count, peripheral blood smear, cytogenetic analysis, immunohistochemistry, and bone marrow biopsy. Chemotherapy is recommended among all patients who develop myelodysplastic syndrome. Surgery is not the first-line treatment option for patients with myelodysplastic syndrome. Stem cell transplantation is usually reserved for patients who are either young or those with high-risk MDS.

# Historical Perspective
Myelodysplastic syndrome was first described in 1900 by Leube.

# Classification
Myelodysplastic syndrome may be classified into several subtypes based on the French-American-British (FAB) classification and the World Health Organization (WHO) classification methods.

# Pathophysiology
Cytogenetic abnormalities involved in the pathogenesis of myelodysplastic syndrome include isolated deletion of 5q, monosomy 7, and monosomy 8. Myelodysplastic syndrome is associated with Fanconi syndrome, Diamond-Blackfan anemia, Shwachman-Diamond syndrome. There are no characteristic findings of myelodysplastic syndrome on gross pathology. On microscopic histopathological analysis, dyserythropoiesis, dysgranulopoiesis, and dysmegakaryocytopoiesis are findings of myelodysplastic syndrome.

# Causes
There are no known direct causes for primary myelodysplastic syndrome. Common risk factors for secondary myelodysplastic syndrome can be found here.

# Differentiating Myelodysplastic syndrome from other Diseases
Myelodysplastic syndrome must be differentiated from other diseases that cause anemia, neutropenia, and thrombocytopenia, such as: aplastic anemia, fanconi anemia, pure red cell aplasia, Shwachman-Diamond syndrome, paroxysmal nocturnal hemoglobinuria, parovirus B19 infection, and vitamin B12 defeciency.

# Epidemiology and Demographics
The incidence of myelodysplastic syndrome is approximately 4.4 to 4.6 cases per 100,000 individuals in the United States. Myelodysplastic syndrome commonly affects older patients. Males are more commonly affected with myelodysplastic syndrome than females. Myelodysplastic syndrome usually affects individuals of the Caucasian race.

# Risk Factors
Common risk factors in the development of myelodysplastic syndrome are past treatment with chemotherapy, radiation therapy, past exposure to tobacco smoke, ionizing radiation, organic chemicals, and heavy metals.

# Screening
According to the United States Preventive Services Task Force, there is insufficient evidence to recommend routine screening for myelodysplastic syndrome.

# Natural History, Complications and Prognosis
If left untreated, a high percentage of patients with myelodysplastic syndrome may progress to develop acute myeloid leukemia or die due to bone marrow failure. Common complications of myelodysplasia include progression to acute myeloid leukemia, bone marrow failure, infection, hemorrhage, and iron overload. Prognosis is generally poor, and the 5-year survival rate of patients with high IPSS score myelodysplastic syndrome is approximately 55%.

# Diagnosis

## History and symptoms
Symptoms of myelodysplastic syndrome include bleeding, easy bruising, shortness of breath, weakness, and fatigue.

## Physical Examination
Common physical examination findings of myelodysplastic syndrome include pallor, hepatomegaly, splenomegaly, lymphadenopathy, fever, and petechiae.

## Laboratory Findings
Laboratory findings consistent with the diagnosis of myelodysplastic syndrome include abnormal complete blood count, peripheral blood smear, cytogenetic analysis, immunohistochemistry, and bone marrow biopsy.

## CT
CT scan may be helpful in the diagnosis of myelodysplastic syndrome. Findings on CT scan of the spine suggestive of myelodysplastic syndrome include osteosclerosis and myelosclerosis.

## MRI
Bone marrow MRI is helpful in the diagnosis of myelodysplastic syndrome. On MRI, myelodysplastic syndrome is characterized by low signal on T1-weighted imaging and high signal on T2-weighted imaging.

## Other Imaging Findings
There are no other imaging findings associated with myelodysplastic syndrome.

## Other Diagnostic Studies
Other diagnostic studies for myelodysplastic syndrome include bone marrow biopsy.

# Treatment

## Medical therapy
Chemotherapy is recommended among all patients who develop myelodysplastic syndrome.

## Surgery
Surgery is not the first-line treatment option for patients with myelodysplastic syndrome. Stem cell transplantation is usually reserved for patients who are either young or those with high-risk MDS.

## Primary Prevention
Effective measures for the primary prevention of myelodysplastic syndrome include avoiding exposure to tobacco smoke, ionizing radiation, herbicides, and pesticides.

## Secondary Prevention
There are no secondary preventive measures available for myelodysplastic syndrome.