PART TWO
Diagnostic cytology
Fig. 16.14 Needle aspirate of reactive gliosis ((A) Papanicolaou x MP; (B) immunoperoxidase using antibody against glial fibrillary acidic protein (GFAP) x MP).
Fig. 16.15 Needle aspirate of low-grade astrocytoma (Papanicolaou x MP).
cellular morphology, but additional factors such as age of the
patient, precise location of the lesion within the brain, and clini-
cal history, especially the presence of a known primary tumor,
may be critical in making the correct diagnosis. Identification
of inflammatory and reactive conditions is possible when neu-
trophils, granulomatous inflammation, or macrophages con-
taining red blood cells, hemosiderin, or myelin debris are seen
(Fig. 16.16). The presentation of lymphoma and metastatic
tumors is essentially the same as in other types of cytologic
specimens. Therefore, the remainder of this discussion focuses
on primary brain tumors.
In contrast to low-grade astrocytomas, the other types of low-
grade primary brain tumors, oligodendrogliomas and ependy-
momas, are hypercellular.3,4 Oligodendrogliomas have round,
regular nuclei with delicate chromatin and moderate amounts
of cytoplasm (Fig. 16.17). The uniformity of the cells and the
occasional presence of calcifications are useful features in iden-
tifying these tumors. Cells of ependymomas are also uniform,
but the nuclei are slightly oval and the cytoplasm often has a
columnar shape. Perivascular pseudorosettes and true rosettes
are occasionally seen. Many ependymomas and oligodendrog-
liomas express GFAP (Fig. 16.17B), and these tumors are usually
positive for panneuroectodermal reagents such as antibody
Fig. 16.16 Needle aspirate of cerebral infarct shows numerous
macrophages (Papanicolaou x HP).
UJ13A. The lymphoid and hematopoietic cell types seen in
reactive conditions, in contrast, are usually negative with these
markers but react with panleukocyte reagents as well as anti-
bodies against the specific types of inflammatory cells. Thus,
antibodies can be helpful in distinguishing these low-grade
neoplasms from non-neoplastic conditions, but reagents that
reliably distinguish between oligodendrogliomas and ependy-
momas are not yet available.
Key features of oligodendroglioma
• Cell uniformity;
• Round regular nuclei;
• Delicate chromatin;
• Moderate cytoplasm; and
• Calcifications.
Key features of ependymoma
• Cell uniformity;
• Oval nuclei;
• Columnar cytoplasm; and
• Perivascular pseudorosettes may be seen.
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