Cell Identification First Quadrimester 2020
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AMERICAN ASSOCIATION OF BIOANALYSTS PROFICIENCY TESTING 11931 Wickchester Ln., Ste 200 - Houston, TX 77043 800-234-5315 - 281-436-5357 - Fax 713-781-5008 PARTICIPANT STATISTICS CELL IDENTIFICATION FIRST QUADRIMESTER 2020 Q1-2020 Hereditary Elliptocytosis Normal circulation of RBCs involves the cells moving through the very tight spaces of the capillary circulation. Normal disc-shaped RBCs cannot pass through these tiny channels without temporarily assuming an elliptical shape. Normally, once these RBCs have passed through these narrow channels, they resume their discoid shape and continue on their journey and stay that way until required to pass through the capillaries again. This transient deformation occurs over and over as the cells circulate. In a normal population, up to 15% of the circulating RBCs can be elliptical or ovoid. Hereditary elliptocytosis (HE), and the slightly less severe, ovalocytosis, are disorders where between 25% and 100% of the RBCs are elliptical or ovoid. Hereditary elliptocytosis is a clinically heterogeneous group of disorders that have in common the presence of oval, elliptical or elongated RBCs in peripheral blood. First described in 1904, hereditary elliptocytosis was recognized as a hereditary condition in1932. The prevalence of HE is relatively low in the United States and Europe affecting only about 1 in every 2,500 people. However, since elliptocytosis may provide resistance against malaria, it is not surprising that HE is considerably more frequent in areas of endemic malaria. In equatorial Africa, the prevalence of common HE has been estimated at between 0.6% and 1.6%. In Southeast Asian populations, the prevalence of Southeast Asian Ovalocytosis (SAO), a variant of HE, is as high as 30%. HE has been divided into three major clinical groups. The first, categorized as Common HE, is mostly reported as an autosomal dominant disorder with no clinical symptoms or just mild to moderate anemia. Jaundice, splenomegaly, and reticulocytosis may be present in some of these patients. A rare, autosomal recessive variant of Common HE, hereditary pyropoikilocytosis (HPP), is characterized by severe hemolytic anemia, jaundice, splenomegaly, and marked spherocytosis and poikilocytosis. A second category of HE is Spherocytic HE (hereditary ovalocytosis). This variant is associated with rounder erythrocytes that show increased osmotic fragility. Spherocytic HE, also called hemolytic ovalocytosis, is a much less common condition in which both round “fat” ovalocytes and spherocytes are present on the blood film. This is an autosomal dominant disorder observed only in Caucasians. These patients exhibit mild to moderate hemolysis, with or without splenomegaly. The third category is Southeast Asian Ovalocytosis (SAO) HE. This variant has been reported in up to 30% of the population of Malayan aborigines in Southeast Asia. It is characterized by spoon- shaped erythrocytes. This variant is characterized by rigid, spoon-shaped RBCs that have, either a longitudinal slit or, a transverse ridge. Patients with SAO have either, no symptoms or at worst, mild clinical manifestations. As described earlier, normal RBCs have the ability to transiently deform as they move thought the capillaries of the circulatory system. HE is clinically heterogeneous disorder where the RBCs have abnormal cytoskeletons and as a result, do not have the necessary flexibility to morph between a discoid and elliptical shape. Once they become elliptical, they remain that way. The spleen removes the elliptocytes from circulation at a much younger age than normal shaped RBCs are, the result being a much shorter life span for elliptocytes than the average 120 day lifespan of normally shaped RBCs. As a result, patients with hereditary elliptocytosis often exhibit some degree of splenomegaly. A number of genes have been linked to HE. The mutations identified in these genes have been identified as affecting the stability of the RBC cytoskeletal scaffold of cells in different, but often, interrelated ways. Two thirds of all cases of HE are caused by genetic defects of genes for either one or both of the erythrocyte membrane proteins α-spectrin, and β-spectrin. Additionally, defects in the erythrocyte membrane proteins 4.1 and 4.2, glycoprotein C and band 3, have also been identified as affecting the stability of the RBC cytoskeleton. Since multiple genes can be involved, there is much genetic variability. Genetic variability explains the wide variability in the severity of the disorder expressed in patients with this disorder. Heterozygotes usually exhibit elliptocytes on the blood smear, but in most instances hemolysis is absent. Homozygotes or compound heterozygotes may have sufficient weakening of the cytoskeleton to cause significant hemolysis accompanied by striking abnormalities in RBC morphology (homozygous hereditary elliptocytosis or hereditary pyropoikilocytosis). The diagnosis of hereditary elliptocytosis is usually made by coupling family history of the condition with an appropriate clinical presentation and confirmation on a blood smear. Definitive diagnosis can involve osmotic fragility testing, autohemolysis testing, and direct protein assaying by gel electrophoresis. Definitive diagnosis of HE is established by identification of the underlying molecular defects of the erythrocyte membrane skeletal proteins. The vast majority of those with hereditary elliptocytois require no treatment whatsoever. They have a mildly increased risk of developing gallstones, which is treated surgically with cholecystectomy if pain becomes problematic. This risk is relative to the severity of the disease. Treatment options for patients with severe HE are with folic acid supplementation, blood transfusion, and/or splenectomy. 17Q3 Immunohematology Page 1 of 3 Cell Identification Specimen 1 Specimen 2 Specimen 3 Specimen 4 Specimen 5 Result No. Flag Result No. Flag Result No. Flag Result No. Flag Result No. Flag Lymphocyte, normal 69 Eosinophil, any stage 180 Elliptocyte/Ovalocyte 180 Basophil, any stage 178 Platelet Clumping 158 Lymphocyte; atypical, Downey, variant 28 Eosinophil, any stage 1 *** Platelet, normal 10 Lymphocyte, reactive 25 PMN with Toxic Granulation/Vacuolization 1 *** Fibrin, Fibrin Strands 4 *** Monocyte, any stage 31 *** Abnormal, would refer 2 Abnormal Lymphocyte, would refer 8 Abnormal Platelet, would refer 2 Metamyelocyte 7 *** Basket/Smudge cell 1 *** Abnormal, would refer 5 Stain artifact 1 *** Abnormal Granulocyte, would refer 2 *** Platelet, giant 1 *** Eosinophil, any stage 1 *** Bacteria 1 *** Myelocyte 1 *** Auer Rods (myeloblast) 1 *** PMN with bacterial inclusion 1 *** * 19 of 22 referees reported Lymphocyte, normal Total Population 180 Total Population 180 Total Population 180 Total Population 180 Total Population 179 Intended result: Lymphocyte, normal Intended result: Eosinophil, any stage Intended result: Elliptocyte/Ovalocyte Intended result: Basophil, any stage Intended result: Platelet Clumping Correct responses are defined as those reflecting agreement among 80% or more of all participants or referees. Unacceptable responses are indicated by "*****" on the Flagging line of each specimen. 17Q3 Immunohematology Page 2 of 3 Cell Identification - Educational Challenge Specimen 1 No. Specimen 2 Teardrop Cell (dacrocyte) 134 Eosinophil, any stage 128 Target Cell (codocyte) 1 Teardrop Cell (dacrocyte) 6 Total Population: 135 Total Population: 134 Intended result: Teardrop Cell Intended result: Eosinophil, any stage *To see the original fullsized immages, please sign on to your data entry sheet at http://www.aab-pts.org/ Cell ID Educational Case History 1Q 2020 History: A 72-year-old gentleman is sent to the Emergency Department by his primary care physician for anemia and passing black stools. He gives a one-month history of intermittently passing black stools; within the past week, all of his stools have been tarry and black. He denies seeing any bright red blood. His past medical history is significant for hypertension, prostate cancer, and chronic intermittent leukopenia. His medications include anti-hypertensive medications, tadalafil, testosterone injections, calcium, and several herbal medications (“for my gall bladder and to keep my cholesterol down”). On physical examination, the patient is healthy-appearing and afebrile. His lung, cardiovascular, and abdominal exams show no abnormalities. CBC results are as follows: WBC 3.5 x 103 /µL, Hgb 8.9 g/dL, Hct 30.7%, Plts 385,000/µL. 17Q3 Immunohematology Page 3 of 3.