Hematology and Clinical Microscopy Glossary - College of American ...

Plasma cells may be bi-nucleated and even
multinucleated. In some rare situations, the
nuclear:cytoplasmic ratio may be so altered and the
cytologic features so atypical, that it is difficult to
recognize the cells as of plasma cell origin.
Myeloid Series
Basophil, Mast Cell
Basophils and mast cells are recognized by
characteristic granules that stain dark blue to black
with Wright-Giemsa which overlap or may obscure the
nucleus. The nucleus of the basophil is segmented and
the chromatin is condensed or smudged. The granules
of a basophil are larger than the azurophilic granules of
a promyelocyte and are often irregular in shape. Mast
cells are usually larger than basophils with a low nuclear
to cytoplasmic ratio and a round or oval nucleus
usually obscured by abundant red-purple granules.
These granules are smaller and more round and regular
than basophilic granules and release histamine upon
stimulation, they are derived from separate progenitor
cells.
Mast cells are usually found in tissues. Basophils and
mast cells are not normally found in body fluids, but
when present, are most commonly associated with
inflammatory conditions, foreign body reactions, and
parasitic infestations.
Eosinophil, Any Stage
The eosinophil is recognized by its characteristic round,
orange-pink to orange-red granules. These are larger
than primary or secondary granules in neutrophils.
Particularly large numbers of eosinophils may be seen in
foreign body reactions, parasitic infection, and
introduction of air into a body cavity.
Neutrophil, Immature (Promyelocyte,
Myelocyte, Metamyelocyte)
Immature stages of the myeloid series are less often
found in body fluids, unless there is an accompanying
increase in those same cells in the peripheral blood.
Patients with chronic myeloid leukemia may have soft
tissue involvement and increased numbers of immature
myeloid cells may be seen in fluids from these patients.
Immature granulocytic (and erythroid) cells can be
found when there is marrow contamination of the fluid,
most commonly in CSF.
Cerebrospinal Fluid (CSF) and Body Fluid Cell Identification
Neutrophil, Segmented or Band
Usually the segmented or band neutrophil is easily
recognized. Often, the nuclear lobes appear eccentric
in cytocentrifuge preparations. In inflammation,
the cytoplasm may contain toxic granules or be
vacuolated. Intracellular bacteria, crystals, or debris
may be seen in pathologic conditions. If inclusions are
present, the more specific identifications such as
“neutrophil /macrophage with phagocytized bacteria”
or “neutrophil/macrophage containing crystal” should
be used.
Neutrophils in body fluids can show morphologic
change due to autolysis, including nuclear pyknosis and
fragmentation, making recognition of cell type difficult.
In particular, these autolytic neutrophils can be
mistakenly identified as nucleated red cells; however,
persistence of a few azurophilic granules in the
cytoplasm provides a clue to the neutrophilic origin.
Neutrophils in samples from the stomach, intestine, or
stool often show striking degenerative changes. For the
purpose of proficiency testing, the identification
“degenerative cell, NOS” should be chosen if the cell
of origin can no longer be recognized.
Mononuclear Phagocytic
Series
Monocyte/Macrophage
Monocytes are bone marrow derived cells that
circulate in the blood. Macrophages arise from bone
marrow derived cells that migrate into tissues and
evolve morphologically. Monocyte/macrophage
morphology in fluids is quite variable, ranging in
continuum from the typical blood monocyte of the
peripheral blood to a vacuolated, activated stage with
the morphology of a typical macrophage. Monocytes
are usually large (12 to 20 μm) with abundant blue-gray
cytoplasm containing and often contain sparse
azurophilic granules. The nucleus is round to oval and
may show indentation, giving it a kidney bean or
horseshoe shape. The chromatin is lacy and small
nucleoli may be apparent.
Macrophages are larger cells (15 to 80 μm) with
abundant cytoplasm showing evidence of active
phagocytosis. This includes ingested material such as
other blood cells or bacteria, hemosiderin, fungi, and
remnants of digested materials as well as cytoplasmic
vacuoles post-ingestion. One or more round to oval
nuclei are present and ocasionally prominent nucleoli
may be seen.
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