Despite its overall rarity, it is the most common type of mature T cell leukemia; nearly all other leukemias involve B cells. It is difficult to treat, and the median survival is measured in months. Large granular lymphocytic leukemia may involve either T-cells or NK cells; like hairy cell leukemia, which involves solely B cells, it is a rare and indolent (not aggressive) leukemia. Adult T-cell leukemia is caused by human T-lymphotropic virus (HTLV), a virus similar to HIV. Like HIV, HTLV infects CD4+ T-cells and replicates within them; however, unlike HIV, it does not destroy them. Instead, HTLV "immortalizes" the infected T-cells, giving them the ability to proliferate abnormally. Human T-cell lymphotropic virus types I and II (HTLV-I/II) are endemic in certain areas of the world. Clonal eosinophilias (also called clonal hypereosinophilias) are a group of blood disorders characterized by the growth of eosinophils in the bone marrow, blood, and/or other tissues. They may be pre-cancerous or cancerous. Clonal eosinophilias involve a "clone" of eosinophils, i.e., a group of genetically identical eosinophils that all grew from the same mutated ancestor cell. These disorders may evolve into chronic eosinophilic leukemia or may be associated with various forms of myeloid neoplasms, lymphoid neoplasms, myelofibrosis, or the myelodysplastic syndrome. Pre-leukemia
Transient myeloproliferative disease, also termed transient leukemia, involves the abnormal proliferation of a clone of non-cancerous megakaryoblasts.
There have been cases of patients who have lost complete sensory perception within the arm after procedures whereas they had full sensory perception before. The most common area for a loss of sensory perception (except where the arm faces a total loss) is between the shoulder and the elbow, since the nerves which provide information from that area to the brain are also those first damaged in the initial causative trauma. Cause
The most common cause of Erbs palsy is dystocia,  an abnormal or difficult childbirth or labor. For example, it can occur if the infants head and neck are pulled toward the side at the same time as the shoulders pass through the birth canal. The condition can also be caused by excessive pulling on the shoulders during a cephalic presentation (head first delivery), or by pressure on the raised arms during a breech (feet first) delivery. Erbs palsy can also affect neonates affected by a clavicle fracture unrelated to dystocia.A similar injury may be observed at any age following trauma to the head and shoulder, which cause the nerves of the plexus to violently stretch, with the upper trunk of the plexus sustaining the greatest injury. Injury may also occur as the result of direct violence, including gunshot wounds and traction on the arm, or attempting to diminish shoulder joint dislocation. The level of damage to the constituent nerves is related to the amount of paralysis. Diagnosis
The appearance of the affected arm (or arms) depends on the individual case.