spleen disease.ppt

Spleen Disease The splenic primordium becomes evident during the fifth week of gestation as an outgrowth of the dorsal mesogastrium,which migrates to the left upper quadrant.The gross appearance of the spleen is the result of its development from multiple anlage,resulting in an organ with multiple clefts.Embryoiogy 12 to 15 cm inlength,4 to 8 cm inwidth and 3 to 4 cmin thickness Average weight isabout 150 to 250 g lies in the shelter of the 9th to 11th rib at the left side of the abdominal cavityAnatomyA pancreas B spleen C duodenum 5 Hepatic portal vein 8 celiac artery(trunk)9 superior mesenteric artery 13 superior mesenteric artery The spleen receives its arterial supply from thesplenic artery,which originates in the celiac axis.After its origin,the splenic artery coursesalong the superior edge of the pancreas,with multiple branches into the pancreaticparenchyma.The artery then g ives off several branches into the spleen,the first being the superior polar artery.There are other arterial vessels to thespleen from the left gastroepiploic artery and the short gastricartery.The splenic veins follow the arterial distribution closely,and the main splenic vein emerges fromthe spleen following a course to join the superior mesentericvein,forming the portal vein.Functions of the SpleenCirculation through the spleen is about 150 to 200 ml/min,or about 5%of the cardiac output.The spleen has traditionally been ascribed four functions:filtration immunological reservoir hematopoietic Filtration abnormal or senescent red blood cells,particulate antigens such as microorganisms or antigen-antibody complexes.Immunological trapping of antigens,homing of lymphocytes,antibodyand lymphokine production,microphage activation,immunoglobulin and antibody synthesis,affects the capability of cellular populations in other lymphoid organs Reservoir Hematopoietic Spleen harbors about one-third of the total platelet mass and a large number of granulocytes.The hematopoietic functions are minimal in humans and much more prominent in other species.Pathological Conditions of the Spleen Splenic Rupture Benign Lesions of the Spleen Maligant Lesions of Spleen Splenic RuptureThe spleen can rupture from three underlying causes:trauma,spontaneous rupture,and pathological rupture.Traumatic rupture of the spleen remains the most frequent indications for splenectomy.Pathologicalcauses of splenic rupture includeinfiltration of the spleen by reactive lymphoidcells or by neoplastic cells.Most cases attributed to spontaneous ruptureof the spleen are actually due to an undiagnosed pathological process.Conditions associated with defective or absent splenic function are grouped together as being conditions of hyposplenism.Those conditions are characterized by the presence of Howell-Jolly bodies in the peripheral circulation.Conditions associated with hypersplenism remain the most frequent indication for elective splenectomy,these can be divided into those conditions in which the spleen is normal but increased destruction of abnormal blood elements causes hypersplenism,and those in which there is a primary disorder of the spleen that results in increased destruction of abnormal blood cells.(Table 1).Pathological Conditions of the SpleenTABLE 1 Disorders Associated With Hypersplenism 1.Disorders associated with sequestration of abnormal blood cells in an intrinsically normal spleen.A.Congenital disorders of erythrocytes 1.Hereditary spherocytosis 2.Hereditary elliptocytosis 3.Hemoglobinopathies B.Acquired disorders of erythrocytes 1.Autoimmune hemolytic anemia 2.Parasitie disease(e.g.,malaria,babesiosis)C.Autoimmune thrombocytopenia D.Autoimmune neutropenia 2.Disorders of spleen resulting in sequestration of normal blood cells A.Disorders of cordal macrophages:Bantis syndrome,storage diseases,parasitie diseases(e.g.,kala-azar),Langerhans cells histiocytosis,malignant histiocytosis B.Infiltrative disorders:leukemias,lymphomas,plasma cell dyscrasias,myeloid metastatic carcinnoma C.Vascular abnormalities D.Splenic cysts E.Hamartomas3.Miscellaneous conditions A.Hyperthyroidism B.Hypogammaglobulinemia C.Progressive multifocal leukoencephalopathySource:Reiman(1997).3Benign Lesions of the Spleen Hemangioma Lymphangioma Peliosis Hemangioendothelioma Hamartomas Other Benign Lesions Nonparasitic Cysts Parasitic Cysts Hemangioma This is the most common benign primary neoplasm of the spleen and can present with splenomegaly Lesions can be solitary or multiple,and are usually blue-red,well-circumscribed nodules.Microscopically,they usually appear as endothelium-lined spaces,and are known as cavernous hemangiomas.Treatment of these lesions is usually splenectomyBenign Lesions of the SpleenGross images:It weighed 425 grams and measured 15 x 9 x 7 cm.A splenectomy was performed.Micro images:representative section of tumor Lymphangioma These lesions are less common than hemangiomas,and are usually subcapsular,appearing as soft,compressible,multicystic lesions on thesplenic