Lymphoid leukemias are a group of leukemias affecting circulating lymphocytes, a type of white blood cell. The lymphocytic leukemias are closely related to lymphomas of the lymphocytes, to the point that some of them are unitary disease entities that can be called by either name (for example, adult T-cell leukemia/lymphoma). Such diseases are all lymphoproliferative disorders. Most lymphoid leukemias involve a particular subtype of lymphocytes, the B cells. Classification
Historically, they have been most commonly divided by the stage of maturation at which the clonal (neoplastic) lymphoid population stopped maturing:
Acute lymphoblastic leukemia
Chronic lymphocytic leukemiaHowever, the influential WHO Classification (published in 2001) emphasized a greater emphasis on cell lineage. To this end, lymphoid leukemias can also be divided by the type of cells affected:

B-cell leukemia
T-cell leukemia
NK-cell leukemiaThe most common type of lymphoid leukemia is B-cell chronic lymphocytic leukemia. B-cell leukemias
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

T-cell leukemias
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.
Meacham syndrome is a rare genetic disorder which is characterized by lung, diaphragmatic and genitourinary anomalies. Signs and symptoms
Often people with this condition are born with both underdeveloped lungs and a herniated diaphragm. Urinary symptoms include a horseshoe kidney
Genital symptoms are different according to the biological sex of the baby, genetic males (46,XX) usually have pseudohermaphroditism, ambiguous genitalia, and perineal hypospadias. Genetic females (46,XX) often have septate uterus and duplication of the vagina. In some cases, karyotype is needed to know the biological sex of the baby.Additional symptoms include neoplasm, cryptorchidism, ventricular septal defect, atrial septal defect, hernia, patent ductus arteriosus, Tetralogy of Fallot, and penile hypoplasia. Causes
This condition is caused by an autosomal dominant missense mutation in the WT1 gene, in chromosome 11. This was found through two half-siblings reported by Suri et al. Epidemiology
According to OMIM, only 12 cases have been described in medical literature. == References ==