MLT GlobeHematology: RBC morphology & inclusions – page 4
89 Hematology MCQs on RBC morphology & inclusions with answers and explanations.
A febrile patient with recurring fever episodes has long, loosely coiled spiral organisms lying between red cells on a Wright-stained smear. The most likely organism is:
Relapsing fever Borrelia are large enough to be seen on routine stained smears during fever spikes. T. pallidum and Leptospira are too thin for routine smears, and Bartonella appears as small rods on red cells.
During an oxidant hemolytic crisis, the smear shows small, dense red cells with irregular outlines and no central pallor. These are best called:
Oxidant damage (as in G6PD deficiency or unstable hemoglobins) forms dense, irregularly shaped contracted cells. They differ from spherocytes by their uneven outline.
Stomatocytes due to an acquired cause are most often associated with:
Acquired stomatocytosis is classically linked to acute or chronic alcohol excess and liver disease. The other conditions are associated with pencil cells, basophilic stippling and macro-ovalocytes.
Which feature best separates a Howell-Jolly body from Pappenheimer bodies on a Wright-stained smear?
A Howell-Jolly body is usually one smooth, round, dark purple DNA remnant. Pappenheimer bodies are small, irregular granules in clusters and are the ones that stain with Prussian blue.
In the sodium metabisulfite slide test for HbS, red cells sickle because the reagent:
Sodium metabisulfite is a reducing agent that deoxygenates hemoglobin under a sealed coverslip, allowing HbS to polymerize and cells to sickle. It does not lyse the cells.
Pappenheimer bodies are most expected on the smear of a patient with:
Pappenheimer bodies are iron granules in red cells, seen when iron is poorly used, as in sideroblastic anemia, or after splenectomy. Iron-deficient cells have no excess iron to form them.
Red cells in Plasmodium vivax infection are often enlarged mainly because this species:
P. vivax (and P. ovale) preferentially invade reticulocytes, which are larger than mature cells, and the infected cell enlarges further. P. falciparum infects cells of all ages without enlarging them.
Brown-black granular pigment inside circulating monocytes and neutrophils in a febrile traveler most suggests:
Phagocytes ingest hemozoin, the digestion product of hemoglobin made by Plasmodium, and it appears as brown-black pigment. Toxic granulation is dark blue-purple and fine, not brown-black.
A patient has microcytosis and a raised RBC count. Which smear finding favors beta-thalassemia trait over iron deficiency?
Thalassemia trait often shows target cells and basophilic stippling with relatively uniform cells. Pencil (elongated) cells and a high RDW are more typical of iron deficiency.
Most people with common hereditary elliptocytosis have:
Most carriers of common hereditary elliptocytosis have elliptocytes on the smear but mild or no hemolysis. Severe forms (such as pyropoikilosis) are uncommon.
Teardrop cells (dacrocytes) are thought to form when red cells:
Cells squeezed through fibrotic marrow or splenic cords may be stretched into a tail and stay deformed. Fibrin strands produce schistocytes, and lipid gain produces target cells or acanthocytes.
Red cells stored for many weeks lose ATP. The typical shape change is:
ATP depletion in stored cells causes shape change to echinocytes and, with further membrane loss, spheroechinocytes and spherocytes. This storage lesion is partly reversible after transfusion.
Irreversibly sickled cells in sickle cell disease stay sickled after reoxygenation mainly because:
Repeated sickling causes membrane loss, dehydration and skeletal damage, so the cell keeps its shape even when the polymer melts on reoxygenation. The cells still contain HbS.
A thin blood film shows small ring forms inside red cells and a few tetrads arranged like a Maltese cross, with no pigment or gametocytes. The most likely organism is:
Babesia forms small rings and a tetrad (Maltese cross) and makes no malaria pigment or gametocytes. Trypanosomes live outside red cells.
Howell-Jolly bodies are common in adults with sickle cell anemia mainly because:
Repeated infarcts cause autosplenectomy, so the spleen can no longer remove nuclear remnants (Howell-Jolly bodies) from red cells.
Spherocytes form mainly because red cells:
When membrane is lost (for example through a defect in HS or removal of antibody-coated membrane by macrophages), the cell takes the shape with the least surface area for its volume, which is a sphere. Excess membrane gives target cells.
Cabot rings, seen in some severe anemias, are thought to be remnants of:
Cabot rings are thin ring or figure-of-eight inclusions thought to come from microtubules of the mitotic spindle. Ribosomal RNA gives basophilic stippling and denatured hemoglobin forms Heinz bodies.
In severe anemia, large bluish-grey polychromatic red cells on the smear mainly represent:
Under strong EPO drive, the marrow releases young reticulocytes early (shift or stress reticulocytes). They still contain RNA, which makes them larger and bluish-grey on Wright stain.
Apart from hyposplenism, Howell-Jolly bodies are often seen in:
Disordered nuclear maturation in megaloblastic anemia leaves nuclear fragments, so Howell-Jolly bodies are common. They are not a feature of the other anemias listed.
Red cells with a slit-like area of central pallor are a typical finding in which blood group-related condition?
Absence of Rh proteins disturbs the membrane and produces stomatocytes with mild hemolysis. The McLeod phenotype is associated with acanthocytes, not stomatocytes.