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CHAPTER 29 ■ Body Fluid Analysis 589
Microscopic Exam ination: Cellular Differentiation can mani est reactive lymphocytes in their CSF. T ese con-
Normal CSF contains a ew mononuclear cells (lymphocytes ditions include subacute and chronic meningoencephalitis,
and monocytes) and rare ependymal cells. T ere is no gen- tuberculous meningitis, listeriosis, purulent encephalitis,
eral agreement as to the signi cance o a ew neutrophilic subacute sclerosing panencephalitis, multiple sclerosis, and
leukocytes in a CSF specimen. bacterial meningitis (recuperative phase).
Cells observed in the CSF resemble comparable cells In addition, viral inclusions may be seen in patients with
seen in the peripheral blood or bone marrow in terms o viral meningoencephalitis, but they are rare.
size and nuclear and cytoplasmic eatures. However, the Mononuclear Phagocytes
appearance o cells in the CSF that are also seen in periph-
eral blood may vary in some details. A Wright-Giemsa’s Monocytes
stain is recommended or the microscopic di erentiation T e morphological appearance o CSF monocytes is similar
o cells. to that o blood monocytes. T ese cells do, however, degener-
Cells that may be encountered in CSF include granu- ate more rapidly than do lymphocytes in vitro. Young mono-
locytes (mature and immature neutrophils, eosinophils, cytic cells have less cytoplasm than do mature cells, and the
and basophils), mature lymphocytes or reactive lympho- cytoplasm is more basophilic. T e nucleus may be rounder
cytes, mononuclear phagocytes (monocytes, histiocytes, or more convoluted in younger cells. Activated monocytic
and macrophages), plasma cells, ependymal cells and cells are larger in overall size, and nucleoli may be observed
choroidal cells, leukemic blasts, and malignant cells (e.g., in the nucleus. T e cytoplasm may be vacuolated, and cyto-
lymphoma cells or tumor cells). Other types o cells can plasmic pseudopods may be seen.
include immature, nucleated erythrocytes and intracel- Less than 2% o the cells seen in normal CSF should be
lular bacteria. Lupus erythematosus (LE) cells are rarely monocytes. T ey are more numerous, especially in degen-
observed in CSF. erated and stimulated orms, in in ants and small children
than in adults. Disease states that can produce an increase in
Lym phocytes monocytes in CSF include tuberculous meningitis, syphilis,
T e eatures o CSF lymphocytes are similar to those o small and viral encephalitis. In addition, meningeal irritation and
lymphocytes in peripheral blood. Normal CSF has a ew subarachnoid hemorrhage can induce increased numbers o
observable lymphocytes. Large lymphocytes and lympho- monocytes. Monocytes also may be seen in leukemic in ltra-
cytes with a darker blue cytoplasm are occasionally seen in tion o the meninges and in ectious states.
normal CSF.
Degenerative changes such as vacuolization, pyknotic Macrophages
nuclear changes, and variations in the staining pattern Te morphological characteristics o macrophages (his-
may be present. Arti actual changes can include overall cell tiocytes) are described in detail in the section describing
shrinkage, a shrunken nucleus or dense clumps o very dark pleural uids. Macrophages can be seen in the CSF rom
coloration in the nucleus, and an irregular cytoplasmic bor- patients with meningitis or meningeal inf ammation,
der caused by slow drying o the specimen on the slide. in ectious diseases, CNS leukemia, lymphoma, malignant
An increased number o lymphocytes in the CSF is typi- melanoma, or other metastatic tumors that have spread to
cally associated with viral in ections but may be seen in a the meninges o the brain or spinal cord. In addition, mac-
variety o disorders. T ese disorders include viral meningo- rophages can be seen in patients who have had hemorrhage
encephalitis, aseptic meningitis syndrome (the majority o in the CSF space or who have undergone pneumoencepha-
cases), ungal meningitis, syphilitic meningoencephalitis, lography, intrathecal chemotherapy, or irradiation therapy
and partially treated bacterial meningitis. Nonin ectious o the brain.
causes o increased numbers o lymphocytes include condi- Macrophages with ingested leukocytes can be observed
tions such as multiple sclerosis. ollowing a surgical procedure that involves the CNS. In
CSF specimens rom patients with acute viral meningitis some pathologic conditions, erythrocytes are randomly
may contain reactive lymphocytes, which must be di erenti- phagocytized. Erythrophagocytosis can be identi ed when
ated rom lymphoblasts associated with leukemia, as well as a an ingested erythrocyte still contains hemoglobin. I ghost
large number o lymphocytes. In addition, patients who have spheres are seen within a macrophage, erythrocyte digestion
undergone chemotherapy and irradiation or conditions can be in erred.
such as leukemia may have reactive lymphocytes in their
CSF subsequent to treatment. Reactive lymphocytes are vari- Polymorphonuclear Segmented Neutrophils
able in shape and maturation, compared with blasts, which Very ew, i any, polymorphonuclear segmented neutro-
are uni orm in shape and degree o maturation. Reactive phils (PMNs) should be observed in the CSF. PMNs may
lymphocytes are also larger, have more cytoplasm, and usu- demonstrate rapid disintegration i the specimen is not
ally lack the large nucleoli o lymphoblasts. examined promptly. T e cells may appear as shadows or totally
Patients with disorders other than acute viral meningitis or disappear in an aged specimen. In addition, the cytoplasm is
patients who have received chemotherapy or radiation therapy usually pale staining, and azurophilic granulation may not be
