20
Fine-Needle Aspiration Biopsy Techniques
Radiologists most often use the Chiba needle of 21 and 22
gauge for transthoracic and transabdominal aspirations. Within
the past several years, and as imaging has become more precise,
radiologists have gotten bolder, employing the Franseen needle
of either 20 or 21 gauge or even a more standard core needle
of 18 gauge. Fine-needle aspiration biopsy of the prostate has
disappeared in the United States, giving way to transrectal ultra-
sound-guided core needle biopsies using a 21-gauge needle.38
Microcore needle biopsy for both palpable and non-palpable
breast lesions has largely supplanted fine-needle aspiration
biopsy, though controversy over which method remains.39,40
In medical centers that specialize in diagnosis and treat-
ment of bone and soft tissue tumors, core needle biopsy is often
combined with FNA.41-44 If the cortex of the bone is intact, it is
necessary to drill a hole through the cortex before aspiration
or the very-large-bore bone marrow-type core biopsy needle is
used. Local anesthesia must be administered before biopsy of
a bone by either fine-needle aspiration or a core biopsy, and
local anesthesia is also useful before attempting FNA of soft tis-
sue tumors, many of which are both large and deeply situated
within the proximal muscles or other soft tissues of the trunk.
As a general rule, the larger the external diameter of the
needle, the greater the likelihood of complications with needle
biopsy. Increasing the radius of the needle likewise increases
the cross-sectional diameter exponentially. If one employs only
the thin-needle technique, there are virtually no complications,
the exceptions being FNA of the thorax (pneumothorax) or
some cases of excessive bleeding with transabdominal aspira-
tion biopsy.45
Training and Planning
Pathologists planning to practice aspiration biopsy should have
a good knowledge of anatomy. They should retrain themselves
in history-taking and physical examination. The majority of
palpable masses amenable to FNA are located in a superficial
position, or they are in an area not in direct relationship to
normal structures, major arteries for example, that would make
the biopsy procedure potentially hazardous. The site of punc-
ture of the aspirating needle should be planned in a manner
that takes into account possible future treatment options. When
aspirating suspected primary malignant tumors, the needle track
should be placed in a location likely to be included in any sub-
sequent excision. While there is very little documented evidence
of needle track seeding following aspiration by the thin-needle
method, selecting the proper approach to the target of a sus-
pected malignant tumor is still important to avoid that potential
complication.
Any patient presenting for needle aspiration biopsy should
have their clinical problem thoroughly reviewed by the aspira-
tor. The pathologist trained to perform needle aspiration biopsy
should take ample time in reviewing the history of the lesion
to be biopsied. Careful consideration of clinical information
from the patient often provides clues as to whether the mass is a
benign or a malignant neoplasm, is metastatic from a previously
treated malignancy, or is unlikely to be a neoplastic process at
all. This is the initial step in the process of arriving at a differen-
tial diagnosis and should not be neglected.
Surgical pathologists-cytopathologists with particular inter-
est in the study of tumors will find the application of needle
aspiration biopsy both a useful and rewarding contribution
to the management of patients with neoplasms. Pathologists
should welcome the opportunity to see patients for that is the
best way to obtain a complete clinical picture and then correlate
it with the biopsy material to arrive at a correct interpretation.
The same approach is equally important for interpretation of
tissue biopsies in surgical pathology.
Basic Equipment
The basic equipment used for rapid and efficient performance of
thin-needle aspiration biopsy are as follows.
1. Cameco Syringe Pistol, Aspir-Gun, or other type
aspiration handle (see Appendix);
2. Ten- or 20-mL disposable plastic syringe with LuerLok
or straight tip, depending on aspiration gun handle
size;
3. Twenty-two- to 27-gauge, 0.6- to 1.0-mm external
diameter disposable needles, 3.8 and 8.8 cm, 15 and
20 cm long, with or without stylus; the needle hub
should be clear;
4. Alcohol skin preparation sponges; betadine skin
sponges for deeper aspirations, transabdominal, tran-
sthoracic, bone (where the cortex is not intact or the
periosteum is elevated), or deep soft tissue;
5. Sterile gauze pads;
6. Microscopic glass slides with frosted ends;
7. Small vial of balanced salt solution and/or RPMI
tissue culture transport media;
8. Suitable alcohol spray fixatives for immediate fixation
of wet smears (note that immediate fixation is not
required when using the Yang rapid Papanicolaou
stain);46
9. Ten- or 20-mL capped tube with 10% neutral buffered
formalin for cell-block or microcore sample fixation;
this is not absolutely necessary as material placed in
RPMI can be converted to a cell block in preference to
the preparation of cytospins as dictated by the initial
evaluation of smears;
10.Optional vial of local anesthesia, 1-2% lidocaine;
topical spray anesthesia for aspirates in children or
intraoral aspirates; vials of lidocaine that dentists use
for local anesthesia and the dispensing equipment
may be useful; see Abele and Miller;47
11.Small vial of buffered glutaraldehyde for fixing
aspirate for electron microscopy if required or
anticipated.
A small plastic tray easily holds all the equipment. Local
anesthesia is required for needle aspiration of transthoracic or
transabdominal masses but is rarely necessary for other clini-
cally palpable lumps, though radiologists and clinicians using
ultrasound to guide aspiration biopsy of the thyroid seem to
prefer the use of local anesthesia. The author considers the use
of both ultrasound and local anesthesia when aspirating pal-
pable masses at any location a totally unnecessary step. How-
ever, those pathologists who have set up free-standing aspiration
biopsy clinics prefer to inject local anesthesia in all patients.
They employ the equipment used by dentists and available from
dental supply houses, 30-gauge disposable needles, 2-mL dis-
posable cylinders of 2% lidocaine hydrochloride, with or with-
out epinephrine, and a reusable metallic injection handle. Local
anesthesia can be very precisely dispensed in the area along the
planned needle track without much tissue distortion that might
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