PART TWO
Diagnostic Cytology
Table 21.3
Guidance for Specific Indications
Organ
Preferred guidance
Alternate guidance
Thyroid
US
peripheral lymph
nodes (head and
neck, supraclavicular,
axillary, groin, etc.)
US
Salivary glands
US
CT
Lung
ct
Fluoroscopy
Mediastinum
CT; Endoscopic US
pleura
US or CT
Fluoroscopy
Liver
US or CT
pancreas
CT, US, or
Endoscopic US
Adrenal
CT
US
Kidney
US or CT
Retroperitoneum
US or CT
pelvis
US or CT
Breast
US or stereotactic
X-ray
mri
Usually this is not a problem; however, it is important to apply
direct pressure to the biopsy site immediately after the needle is
removed to reduce the chances of bleeding from these vessels.
For superficial biopsies of the thyroid, peripheral lymph
nodes, etc., the skin is prepared by swabbing with alcohol or
chlorhexidine. When ultrasound is used, the transducer is
covered with a plastic or latex cover and prepared in a similar
fashion. When small (21- to 27-gauge) needles are used, local
anesthesia is usually not required.
FNAB of deep thoracic, abdominal, and pelvic masses involves
additional considerations that are not routine when superficial
or palpable masses are aspirated. Deep biopsies in the chest,
abdomen, or pelvis should be performed using strict sterile tech-
nique. Local anesthesia of superficial and deep tissues should
also be utilized to minimize patient discomfort and encourage
maximal patient cooperation. The importance of effective use of
local anesthesia to the overall success of the biopsy procedure
cannot be overemphasized.
An important aspect of image-guided biopsy is the ability to
provide permanent documentation of the biopsy needle at the
biopsy site. When necessary, imaging guidance should be used
to selectively sample specific sites with a mass, avoiding areas of
obvious necrosis, where diagnostic yield is likely to be poor.
Thyroid, Peripheral Lymph Nodes, Salivary Gland,
and Superficial Soft tissue Masses
US is preferred for localization and biopsy guidance for most
superficial soft tissue masses, including those arising in the thy-
roid and parathyroid glands; the parotid and submandibular
salivary glands; cervical, axillary, and inguinal lymph nodes;
and superficial masses elsewhere in the body. Biopsy of super-
ficial masses is among the most common image-guided FNA
biopsies and employs a similar technique. Scans of the area of
interest are first performed to confirm the location, depth, and
features of the target lesion, as well as the relationship to major
blood vessels or other vital structures. The skin is then prepared
with alcohol or chlorhexidine. The choice of needles is largely
a matter of personal preference, and most often involves use of
standard 21- to 27-gauge needles. With needles of this size, local
anesthesia is usually not required. The needle is introduced
under direct sonographic guidance into the selected target and
capillary action and/or aspiration are used to remove the sample.
In most cases, a free-hand technique is utilized, although biopsy
guides to steer the needle on a selected path are sometimes used.
Depending on the preference and experience of the physician
performing the biopsy the needle may be introduced parallel
to the ultrasound beam or in a path more nearly perpendicular
to the beam. Less experienced operators may find that the latter
approach permits more confident identification of the needle
path, allowing for correction of needle position as it approaches
and enters the target. Once the needle enters the target, image
documentation of the sampling site is performed (Fig. 21.2A)
and sampling is completed. The procedure is repeated as neces-
sary until an adequate sample is obtained. To minimize bleed-
ing, pressure is applied directly to the biopsy site as soon as the
needle is withdrawn. This is especially important when vascular
organs, such as the thyroid are biopsied. At the completion of
the procedure, scans of the biopsy site are performed to docu-
ment any extravasation or other complication of the procedure.
With adequate samples, the sensitivity and specificity of
FNAB in the evaluation of thyroid masses generally exceed 90
and 70%, respectively. The adequacy of samples obtained by
FNAB, however, is highly variable, with inadequate sampling
reported in from less than to 10% to more than 30% of biop-
sies. The availability of an on-site cytopathologist to evaluate
the adequacy of samples as they are obtained, and the skill and
experience of the individual performing the biopsy are impor-
tant in achieving the highest possible rate of adequate speci-
mens. The impact of needle size on adequacy of FNAB samples
has been investigated and found to have little effect.7 Although
many superficial masses are palpable and may be biopsied with-
out image guidance, data suggest that even for palpable masses,
ultrasound guidance improves sensitivity and specificity.2
Hematoma formation following thyroid FNAB occasion-
ally occurs, but serious complications including tumor seed-
ing of the needle track and infection are rare. Transient vocal
cord paralysis is a reported complication with one large study of
10,974 biopsies noting 4 occurrence of 0.04%.8
Breast
Accurate localization of nonpalpable breast masses is possible
with stereotactic radiographic methods, US, and MRI. Although
FNAB continues to play a role in the initial assessment of pal-
pable breast masses, core biopsy or vacuum-assisted tissue
sampling techniques are most often used for diagnosis of non-
palpable masses detected by mammography.9,10 For core tissue
sampling methods US is preferred if the mass is visible with
US. Lesions not seen with US may be biopsied with stereotactic
X-ray or MRI guidance.
Lungs and Pleura
FNAB of lung and pleural masses is commonly performed with
CT or fluoroscopic guidance (Fig. 21.1A).11
For biopsy of pleural
masses and lung lesions that abut the pleura US guidance is also
604
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