Other conditions causing a low platelet count
Other conditions that can cause a low platelet count in the neonate include bacterial and viral infection, disseminated intravascular coagulation and other rare congenital conditions associated with a low platelet count. Pathophysiology
Platelets have many proteins on their surface. Each person has a different set of proteins, which are inherited from their parents. These different platelet proteins make different platelet groups, just like different proteins on red blood cells make different blood groups. These differences do not affect how the platelets work. However, if a baby inherits a protein that is found on the fathers platelets but is absent from the mothers platelets, the mother may respond to this foreign protein by developing an antibody that fights against it.This antibody may pass from the mothers blood into the babys blood and attach to the babys platelets. This antibody destroys the babys platelets and suppresses production of fetal platelets, they are also thought to weaken the blood vessel walls (vascular integrity) and affect production of new blood vessels (angiogenesis). This results in an increased risk of bleeding for the baby, and this can lead to the babys death. The mothers antibodies can remain in the babys bloodstream for weeks, and bleeding can occur in the baby before birth (fetal), during birth or after birth (neonatal).A number of different proteins can cause NAIT, about 80% of cases are caused by antibodies against platelet antigen HPA-1a, 15% by anti-HPA-5b, and 5% by other antibodies (e.g. HPA-1b, HPA-15, HPA-3 and HPA-9b).
Sea-blue histiocytosis is a cutaneous condition that may occur as a familial inherited syndrome or as an acquired secondary or systemic infiltrative process. : 720

Causes
It can be associated with the gene APOE.It can also be acquired. Sea-blue histiocyte syndrome is seen in patients receiving fat emulsion as a part of long-term parenteral nutrition (TPN) for intestinal failure. Pathophysiology
The high lipid content in the blood leads to excessive cytoplasm loading of lipids within histiocytes. The subsequent incomplete degradation of these lipids leads to the formation of cytoplasmic lipid pigments. High lipid content may also cause membrane abnormality of the hemopoietic cells which is recognized by macrophages and therefore, increased accumulation within the bone marrow. These lipid laden histiocytes appear blue with May-Giemsa/PAS stain hence the name of Sea-Blue Histocyte Syndrome. Sea-blue histiocytosis is also seen in lipid disorders. Diagnosis
See also
Non-X histiocytosis

References


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