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The presence of blast cells or immature stages of hematopoietic cell lines are significant abnormal findings in any spinal fluid sample. However, the presence of nucleated red blood cells is the result of bone marrow contamination during the spinal tap.

Pappenheimer bodies are seen in the cytoplasm of mature and immature erythrocytes on a Wright's stained smear. They are composed of degenerating cellular remnants, which contain iron. Pappenheimer bodies are most likely caused by accelerated red cell division, or impaired hemoglobin synthesis. Pappenheimer bodies appear as small dark purple granular bodies of varying size frequently clustered in groups of two, three or more near the edge of the cell.

To verify that red cell inclusions contain iron, it is necessary to use an iron stain, such as Perl's Prussian blue. The iron-containing granules are called siderotic granules. A mature erythrocyte containing siderotic granules is referred to as a siderocyte, while an immature (nucleated) erythrocyte containing siderotic granules is known as a sideroblast. A Pappenheimer body is a siderotic granule which is visible on Wright stain. All Pappenheimer bodies are Prussian blue positive, but not all siderotic granules are visible on Wright's stain as Pappenheimer bodies.

Although the nucleus has been extruded, the reticulocyte is still considered immature because it retains numerous organelles needed for hemoglobin production, such as ribosomes, mitochondria, and fragments of the Golgi apparatus. The reticulocyte is slightly larger (10 microns) than the mature erythrocyte. A reticulocyte normally remains in the bone marrow for one or two days before entering the circulation and its final 24 hours of maturation. The red cell is mature when hemoglobin production is complete and the organelles have disintegrated. Reticulocytes normally make up 0.5 - 1.5% of the peripheral blood red cells. They appear blue/gray on the Wright's stained smear. The residual RNA in the cytoplasm causes the blue/gray color. The terms, polychromasia or polychromatophilic, are used to describe these cells on a Wright's stained preparation. A supravital stain such as new methylene blue N or brilliant cresyl blue is used to stain reticulocytes for an actual count.

Another example of tumor cells under higher magnification, showing large cells with loose immature chromatin structure and ill-defined cytoplasm.

A thin area of a slide taken from a patient who has chronic lymphocytic leukemia, which is characterized by an increased number of small lymphocytes in the bone marrow. At this power, numerous small dark cells similar in appearance to immature red cells are seen, but can be quickly confirmed as lymphocytes when viewed under oil. The actual M:E ratio is normal, since lymphocytes are not included in the final ratio. The arrows show several cell most likely representing small lymphocytes. Some small lymphocytes are normal in the bone marrow.

Jaundice was recognized in a day-old infant. Notice particularly the size variation (anisocytosis) of the erythrocytes on the infant's peripheral smear. What does this observation mean? Does it provide immediate information that might serve as guidance in expediting diagnosis and treatment? Note that normal-sized red blood cells, microcytes, microspherocytes, macrocytes, and nucleated red blood cells are all present. Red cell variations are expected findings in healthy neonates, but the variations here are exaggerated. Hyposplenic functional features may appear, including acanthocytes, spherocytes, and possibly Howell-Jolly bodies, especially if hemolysis is particularly vigorous. A high (3-7%) reticulocyte count is not unusual during the first three or four days after birth, however, the marrow in this jaundiced infant is proliferating vigorously in response to hemolysis. A call for more red cells is urgent. Immature red cells (in the form of nucleated red cells) and red cells with stippling of RNA (basophilic stippling) are readily identified. Red cell maturation sequence has not been totally processed in the marrow nor is all residual red cell debris removed by the spleen. In the lower photograph are reticulocytes stained by supravital stain (new methylene blue). Basophilic stippling (specks of RNA) stains with both supravital stains and with routine Wright-Giemsa stain.

In addition to the amount of hemoglobin present, the color of the cell must also be considered. Completely mature red cells appear buff-colored, while slightly immature non-nucleated red cells (reticulocyte stage) appear blue/gray on Wright's stained smears due to the presence of residual ribonucleic acid (RNA).The terms used to describe these cells are polychromasia or polychromatophilia. Polychromatophilic cells are frequently larger in size than mature red cells and can be distinguished from both types of macrocytes by this distinctive color.

In addition to the sperm in the center of this field, a round cell is seen at center right (1 o’clock) and red cells at center bottom (6 o'clock) and left (9 o’clock). Red cells have a round, smooth appearance when compared to the grainy appearance of the round cells. Round cells may be either immature sperm or white cells.

A false negative reaction is no induration after a TST even if the person is infected with Mycobacterium tuberculosis. Some causes of this are: weakened immune system,recent, old or overwhelming TB infection,immature immune system (<6 months of age),some viral illnesses,recent live-virus vaccinations,incorrect TST administration or interpretation.

The term leukemoid reaction is used to describe peripheral white blood cells that on the stained blood smear may have some resemblances to leukemia cells. Quantatively in a leukemoid reaction, the neutrophil count is >50,000 cumm with more immature cells, particularly myelocytes, than are usually present in toxic left shift syndromes. The presence of immature cells in a leukemoid reaction awakens thoughts of leukemia. Great care must be taken to make a distinct differentiation between aberrant white blood cell proliferations and a benign but exaggerated granulocytic proliferative response. Our material is from a 1-month-old girl with Down's syndrome. Her total white blood count was 37,000/mm3 interpreted as leukocytosis with left shift. Leukocytosis with a left shift, and leukemoid reactions with high alkaline phosphatase are conditions to be mindful of in patients with Down's syndrome. The alkaline phosphatase score is high in leukemoid reactions, low in granulocytic leukemia.

Plasma cells are uncommonly observed in the peripheral blood smear.They are normal constituents of lymph nodes, spleen, connective tissue and bone marrow. The presence of plasma cells in the peripheral blood is indicative of a large number of conditions mostly related to infections , immune disorders, malignancies, toxic exposures, hypersensitivity reactions and their responses.Although mature plasma cells have a distinct appearance, they still may be confused morphologically with immature plasma cells and other cells with inclusions, reactive changes or nucleated red bloods cell with altered identities.In the upper and lower photographs are plasma cells with features mindful of myeloma cellsThe large myeloma cell in the upper photograph has an eccentric immature nucleus with a muddy chromatin pattern.Note also clumping and stacking of the erythrocytes, bordering on rouleaux formation ,implicating an increase in plasma gamma globulin.The plasma cell with the double nucleus in the lower photograph is particularly suggestive of myeloma.Further studies are in order including a bone marrow examination where at least 30% of bone marrow cells should be variations of mature and immature plasma cells.Serum electrophoresis will reveal a monoclonal globulin spike, and light chains in excess of 1.0 gm/24 hours may be seen in the urine.The presence of lytic bone lesions is a convincing clinical clue.With these findings in combination, a diagnosis of myeloma can be made with assurance.