{"id":2055,"date":"2009-12-27T14:45:09","date_gmt":"2009-12-27T19:45:09","guid":{"rendered":"http:\/\/insidesurgery.com\/?p=2055"},"modified":"2013-08-17T17:03:08","modified_gmt":"2013-08-17T21:03:08","slug":"multiple-myeloma","status":"publish","type":"post","link":"https:\/\/insidesurgery.com\/2009\/12\/multiple-myeloma\/","title":{"rendered":"Multiple Myeloma"},"content":{"rendered":"
Pathophysiology<\/strong><\/p>\n 1)<\/strong> infiltration of bone marrow by malignant plasma cells that secrete a partial or whole immunoglobulin called the M component or paraprotein 2)<\/strong> five subtypes – IgG, IgA, IgD, IgE, and light chain 3)<\/strong> clinical course follows a biphasic pattern – initially chronic and then an accelerated late phase<\/p>\n Signs and Symptoms<\/strong><\/p>\n 1)<\/strong> recurrent infections (pneumonia, Toxoplasma, and Pneumocystis 2)<\/strong> pathologic fractures 3)<\/strong> bleeding episodes 4)<\/strong> lymphadenopathy\/organomegaly 5)<\/strong> neurologic deficits 6)<\/strong> chronic renal failure 7)<\/strong> usually presents with bone pain in ribs or vertebrae<\/p>\n Characteristic Test Findings<\/strong><\/p>\n Laboratory<\/em> – 1)<\/strong> monoclonal spike on protein electrophoresis 2)<\/strong> Bence Jones proteins in urine (kappa or gamma immunoglobulin light chains) 3)<\/strong> anemia 4)<\/strong> hypercalcemia 5)<\/strong> hyperuricemia 6)<\/strong> increased sed rate Radiology<\/em> – 7)<\/strong> “punched out” lytic bone lesions (especially in skin and flat bones) or diffuse demineralization<\/p>\n Histology\/Gross Pathology<\/strong><\/p>\n <\/p>\n 1)<\/strong> Dutcher bodies (intranuclear inclusions of immunoglobulin protein droplets) in plasma cells 2)<\/strong> Russell bodies (cytoplasmic inclusions of immunoglobulin protein droplets) in plasma cells 3)<\/strong> plasmablasts and variants – flame cells, binucleated plasma cells 4)<\/strong> plasma cells > 30% of bone marrow 5)<\/strong> renal tubular casts of light-chain protein fragments 6)<\/strong> RBC rosette formation<\/p>\n Associated Conditions<\/strong><\/p>\n 1)<\/strong> large exposure to ionizing radiation 2)<\/strong> amyloid deposition 3)<\/strong> increased incidence in chronic infection (osteomyelitis) and inflammatory conditions (lupus) 4)<\/strong> nephrocalcinosis 5)<\/strong> hyperviscosity syndrome 6)<\/strong> translocation of chromosomes 11 and 13 7)<\/strong> superimposed AML or myelodysplastic syndrome<\/p>\n Biochemistry<\/strong><\/p>\n 1)<\/strong> translocation of proto-oncogene bcl-1 on chromosome 11 places it next to immunoglobulin heavy-chain gene on chromosome 14 2)<\/strong> development may require a “two-hit” process 3)<\/strong> myeloma cells secrete cytokines that recruit osteoclasts only and thus cause purely lytic bone lesions<\/p>\n Inheritance\/Epidemiology<\/strong><\/p>\n 1)<\/strong> 7,500 cases per year in USA 2)<\/strong> blacks to whites, 2:1 3)<\/strong> mean age at diagnosis, 65 years 4)<\/strong> most common variant is IgG myeloma with mean survival of 3-4 years with treatment (other variants more aggressive with shorter survival times)<\/p>\n Treatment<\/strong><\/p>\n 1)<\/strong> radiation to isolated bone lesions 2)<\/strong> alkylating agent (melphalan, cyclophosphamide) and prednisone given as pulse doses 3)<\/strong> stem cell transplant and bone marrow transplant have shown great promise 4)<\/strong> thalidomide in refractory cases<\/p>\n Tips for USMLE<\/strong><\/p>\n 1)<\/strong> if M component is mentioned, think multiple myeloma 2)<\/strong> if a 67 year old black male has had three cases of pneumonia in the past 16 months and now has renal insufficiency and a radiograph of his skull shows punched out lesions, think multiple myeloma<\/p>\n","protected":false},"excerpt":{"rendered":" Pathophysiology 1) infiltration of bone marrow by malignant plasma cells that secrete a partial or whole immunoglobulin called the M component or paraprotein 2) five subtypes – IgG, IgA, IgD, IgE, and light chain 3) clinical course follows a biphasic pattern – initially chronic and then an accelerated late phase Signs and Symptoms 1) recurrent […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_exactmetrics_skip_tracking":false,"_exactmetrics_sitenote_active":false,"_exactmetrics_sitenote_note":"","_exactmetrics_sitenote_category":0,"_genesis_hide_title":false,"_genesis_hide_breadcrumbs":false,"_genesis_hide_singular_image":false,"_genesis_hide_footer_widgets":false,"_genesis_custom_body_class":"","_genesis_custom_post_class":"","_genesis_layout":"","footnotes":""},"categories":[5156,5123,5300,63],"tags":[687,688,684,685,683,690,686,689],"yoast_head":"\n