Chromatin Information and Courses from MediaLab, Inc.

Seven mesothelial cells are seen in this slide. Notice that all of the nuclei have a distinct shape with no evidence of irregular division. Chromatin pattern is typical of cells that originate in the tissues. Cytoplasm is irregular and some pseudopods are evident, especially in the lower portion of the field.

The arrow in this slide is pointing to a monocyte. The nucleus has an open chromatin pattern which gives it a spongy appearance. There is another monocyte in the lower right corner of the field. The other two cells could be classified as macrophages (histiocytes) because the nucleus is oval or kidney bean-shaped and the cytoplasm is very irregular. After circulating in the blood for one to three days, monocytes enter the tissues. The tissue form of the monocyte is called a macrophage or histiocyte.

The arrow in this slide indicates the location of another example of a blast that was seen in a spinal fluid sample. Notice the two prominent nucleoli in the nucleus of this blast. The other three cells in the field are mature lymphs. Notice that the chromatin pattern in the mature lymphs is more clumped than the chromatin in the blast cells.

Another example of a malignant cell. This cell has a smooth chromatin pattern similar to the chromatin pattern commonly seen in blast cells. This cell has a high nuclear to cytoplasm (NC) ratio which is typical for malignant cells. No nucleoli are visible in this cell although malignant cells often have large nucleoli.

This slide shows an example of the youngest cell in the megakaryocyte series, the megakaryoblast. Megakaryoblasts have a fine chromatin structure with multiple nucleoli, and scant basophilic cytoplasm. Cytoplasmic tags are frequently seen. It may vary 20-50 microns in diameter.

An occasional plasma cell is a normal finding in the bone marrow. The nuclear chromatin pattern is coarse, the cytoplasm is varying shades of blue with a "hoff" or light staining area adjacent to the nucleus.

The large cell in the center of this slide is a macrophage, which is normally present in low numbers in the marrow. Macrophages have a loose chromatin pattern and on some smears the nucleoli appear blue/green. The cytoplasm is irregular in shape and contains granules.

Lymphocytes "transform" in response to antigenic stimuli.Their nuclei becomes larger with more open chromatin and a greater degree of nuclear folding.The cytoplasm becomes abundant, the number of azurophilic granules may be increased and vacuoles may be present.The cytoplasmic membrane may be easily indented by surrounding red blood cells, resulting in a scalloped appearance of the cell's outer edge.These lymphocytes may also be referred to as reactive, activated or stimulated.

The eosinophil nucleus has a coarse, clumped chromatin pattern. There are normally only two lobes present, and often they are bigger than those of the seg.

The nucleus of a band neutrophil is sausage or band-shaped (U-shaped).Sometimes it appears folded or twisted, thus making identification more difficult.The nucleus stains a deep purplish-blue color, and the nuclear chromatin appears condensed, coarse, and clumped.

The chromatin pattern is not as dense as that of the small lymphocyte, but even so the nucleus appears hard and flat.

Monocytes have generally lighter staining nuclei than do other leukocytes. The nucleus stains a pale bluish-violet, and the chromatin is fine and skein-like.

Another nucleus of a neutrophil with a band-shaped nucleus. The chromatin pattern in this cell is more normal in appearance than the chromatin seen in the previous slide, but is still coarse.

The band-shaped form seen in the center of this field is typical of the bilobed cells seen in Pelger-Huet. Notice the chromatin structure is almost smooth in appearance, showing little parachromatin. Normal bands have more clumping in the chromatin pattern.

Illustrated in the upper and lower photographs are two-lobed, eye glass ("pince nez") nuclei of neutrophils typical for patients with Pelger-Huet anomaly. In addition to the characteristic two lobes connected by a delicate bridge, the dense, homogeneous nuclear chromatin helps to define Pelger-Huet anomaly. Since the peripheral blood smear did not support the diagnosis of appendicitis in this patient, and since abdominal pain localized to the right lower quadrant never developed, the boy was hydrated with intravenous fluid and observed. After hydration, his constitutional symptoms improved and the abdominal pain subsided. In fact, the lad was back on the ski slopes the next afternoon. People entering high altitude where the humidity may be very low are susceptible to dehydration and may experience symptoms related to mountain sickness. Therefore, close observation and hydration may be the best practice in monitoring patients with stories and findings similar to this one. A further lesson here is that technologists must be alert to the possibility of Pelger-Huet anomaly if a high white blood cell count with a high percentage of band neutrophils with strikingly uniform morphology and without toxic granulation are found. Inappropriate therapy or an invasive procedure as was contemplated here may be avoided by a proper smear assessment and clinical corroboration.

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.