ON
C
Fine Needle Aspiration of
Various Organs and Body Sites
chapter
24
Lymph Nodes: Cytomorphology
and Flow Cytometry
Nancy a Young and Tahseen Al-Saleem
Contents
In tro d u c tio n
T h e C la ss ific a tio n o f th e L y m p h o id N e o p la sm s
T e c h n iq u e s
p ra c tic a l G u id e lin e f o r t h e C y t o p a th o lo g is t
C o lle c t io n a n d C y t o lo g ic p r e p a r a t io n
N o n - H o d g k in s L y m p h o m a
F lo w C y t o m e t r y O v e r v ie w
N o rm a l L y m p h N o d e : S tru c tu re a n d Im m u n o p h é n o ty p e s
H is t o lo g y
C h a lle n g e s a n d D ia g n o s tic P itfa lls
C
1 ’
c
C y t o lo g y
1 I i i ■
r
i
i
i
k
i
i
i • i
k
i
i
N o n -n e o p la s tic L y m p h a d e n o p a th y
L a c k o f A r c h it e c t u r e
F o llic u la r H y p e rp la s ia
p re s e n c e o f B e n ig n H o s t C e lls
V ira l I n f e c t io n s
A b e r r a n t p h e n o ty p e s
I m m u n e D is e a s e s
C o n c lu d in g R e m a rk s
S u p p u r a tiv e L y m p h a d e n it is
G r a n u lo m a t o u s L y m p h a d e n it is
Introduction
Fine-needle aspiration (FNA) is a well-established procedure
for the evaluation of lymphadenopathy, which occurs in a wide
spectrum of diseases including reactive conditions, infections,
and primary and metastatic malignancies. The morphologic cri-
teria for the diagnosis of metastatic tumors and infections in
aspirates from lymph nodes are similar to those in other body
sites. Therefore the major focus of this chapter will be devoted
to the use of cytomorphology along with flow cytometry (FCM)
and other ancillary studies in the evaluation of lymphoprolif-
erative disorders, a particularly challenging area in the field of
cytopathology.
The current World Health Organization (WHO) classification
of hematopoietic and lymphoid tumors has incorporated the
progress in molecular pathology and genetics.1
Thus lymphoma
diagnosis is a combination of pattern and cytomorphology in
addition to immunophenotypic, genotypic, and clinical features.
Numerous references in the pathology and cytopathology
subspecialty literature have established the role of FNA in the
evaluation of primary and recurrent non-Hodgkin's lymphoma
(NHL), particularly when combined with immunophenotypic
and molecular genetic studies.2-35 Although the diagnosis of
lymphoma by FNA is becoming widely practiced, its reliabil-
ity depends on the expertise of the pathologists and the colle-
gial interaction among cytopathologists, surgical pathologists,
hematopathologists, and clinicians.26,35,36 Presently, the diagno-
sis of lymphoma by FNA is still often followed by a confirma-
tory excisional biopsy in clinical practice.35,37
Surgical excision of deep-seated lesions
is
an invasive
procedure and even biopsies of superficial lymph nodes are not
without risk. For example, iatrogenic injury to the spinal acces-
sory nerve is the most frequent complication of lymph node
biopsy in the posterior cervical triangle of the neck due to the
superficial course of the accessory nerve.38,39 The role of FNA in
the evaluation of lymphadenopathy is widely accepted to avoid
the complications of surgical lymph node biopsies. In addition
to its advantages in terms of cost, convenience, rapid turnaround
time to diagnosis, and ability to perform immediate adequacy
readings with triage to FCM, culture, and other ancillary studies,
FNA also offers the ability to sample multiple nodes, while open
biopsy of different anatomic sites is not feasible.40
Thus, regardless of the institutional policy the cytopatholo-
gist is increasingly faced with the need to evaluate a lymphoid
lesion. These lymphoid specimens may not necessarily come
from a lymph node FNA but from other organs or soft tissue
masses. Use of supplemental cell blocks and/or core needle
biopsies may be complementary to cytologic preparations and
provide a minimally invasive way of obtaining additional archi-
tectural information. In the future, FNA may become even more
useful as we identify by DNA microarray technology patterns
of messenger RNA expression in cells that produce "molecular
signatures" unique to various tumors, permitting more precise
disease definition and recognition of factors predicting progno-
sis and response to treatment.41 Given the suitability of FNA in
obtaining tissue for molecular studies, one can foresee a future
in which information obtained from these tests will further aug-
ment the role of FNA in lymphoma management and research.
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