Page 2238 - Cote clinical veterinary advisor dogs and cats 4th

1114 Fine-Needle Sampling for Cytopathologic Analysis: Lung

• Excessive compression when spreading cells
on slide (cells may lyse)
VetBooks.ir cells on slide (clumped cells cannot be
• Inadequate compression when spreading
evaluated)
• Sampling nondiagnostic areas, such as areas
adjacent to the mass or areas of necrosis or
fluid associated with a mass that contains
solid tissue (may miss diagnostic cells)
• Having open container of formalin nearby
(can alter staining of the cells, altering
morphology and rendering smears useless)
• Contamination of the sample with materials
such as ultrasound gel (or starch granules
from powdered gloves, which are no longer
available in the United States and limited
use in Canada) FINE-NEEDLE SAMPLING FOR CYTOPA-
• Copious blood contamination can make THOLOGIC ANALYSIS: LUNG Lung FNA in a
cat. Ciliated respiratory epithelial cells (arrows) can
cytologic interpretation difficult to impos- be present among inflammatory cells in lesions as
sible. A bloody sample may prompt repeat shown. They can also be present in FNA of normal
sampling, but the patient’s status should lung. Free cilia can exfoliate and resemble extracellular
be considered. If iatrogenic hemorrhage thin bacteria; caution is to be used when interpreting
is sufficient to obscure microscopic inter- these aspirates. FINE-NEEDLE SAMPLING FOR CYTOPATHO-
pretation, but the patient is stable with LOGIC ANALYSIS: LUNG Lung FNA equipment.
Bottom, 6-mL syringe with Luer-Lok. Middle, Four
no evidence of inordinate hemorrhage/ needles, top to bottom: 22 gauge, 1.5 inch; 22
hemothorax, an additional collection can be • If using thoracic radiographs, use rib space gauge, 1 inch; 20 gauge, 1 inch; 25 gauge, 1 inch.
attempted. and other landmarks to identify the area just Top, Microscope glass slides.
• Using heat fixing to help cells stick to the overlying the lesion.
glass slide. More often than not, this can • If diffuse disease is present, aspirate on either
significantly alter cell morphology. Air-drying side of the chest between the 7th and 9th
is recommended (see procedure, below). ribs approximately one-third of the height
• Failure to label the glass slides with appropri- of the chest down from the spine. disease and less so for solid masses. For
ate patient identifier and location of the site • Insert the needle through the skin only, just focal disease, it should be obtained with
sampled caudal to the area overlying the lesion. bronchoscopic guidance.
• If sending to a reference laboratory, failure to • Advance the needle forward to just in front • Surgical biopsy (thoracotomy, thoracoscopy):
place the glass slides in appropriate protective of the rib overlying the lesion. much more invasive, expensive, with greater
packaging • Gently plunge the needle through the morbidity, but optimal diagnostic yield and
intercostal muscles into the area of the lesion potential for therapeutic benefit
Procedure (estimated or as confirmed by imaging). • Relative merits of cytopathologic versus
• Locate nodule or consolidation on thoracic • Optional step: without redirecting to the histopathologic evaluation
radiographs and assess side, gently move the needle in and out by
○ Side of thorax for lesion (right or left) a few millimeters. Pearls
○ Rib space of lesion • Apply repeated suction to the syringe several • Diagnostic yield for solid lesion is up to
○ Height of lesion (e.g., just above the times in rapid succession (see Video). 85% but is less for diffuse lung disease.
costochondral junction) • Pull the needle straight out of the animal. • Fine-needle aspirates of normal lung typically
○ Distance from skin to lesion (to choose • Remove the needle from the syringe. contain some degree of hemorrhage ± rare
needle length as well as guide placement) • Fill the syringe with air and reattach to the macrophages ± few respiratory epithelial cells.
○ Note surrounding structures (may abort needle. • In addition to cells of interest, other materials
procedure if vital structures very close to • Expel the contents of the needle, and prepare (e.g., mucus, ruptured cellular debris) may
lesion) the slides as for FNA of SQ mass. be seen.
• Sedation or anesthetic induction (if desired) • The procedure may be repeated if necessary. • Mixed inflammatory cells and hemosidero-
• For conscious animals, appropriate skilled Because diagnostic yield is reduced with phages may coexist with neoplastic cells in
restraint diffuse disease (as compared to a solid lesion), tremendously variable proportions.
• Oxygen supplementation provided for immediate repetition on the other side of • Larger needles produce more cells for
animals with diffuse lung disease or dyspnea the chest is useful. diagnosis but are also associated with greater
• Procedure may be performed with animal morbidity.
in sternal or lateral recumbency, depending Postprocedure
on lesion location. Animals with respiratory • Periodically monitor respiratory rate and SUGGESTED READING
disease are often more comfortable in a effort and mucous membrane color for a DeBerry JD, et al: Correlation between fine-needle
sternal position, which is generally preferred few hours after the procedure. aspiration cytopathology and histopathology of the
by the authors. • There is no need for routine repeat imaging lung in dogs and cats. J Am Anim Hosp Assoc
• Clip and disinfect the area of the skin studies, but these may be warranted by 38:327-336. 2002.
overlying the lesion. worsened respiratory distress. AUTHORS: Ryan M. Dickinson, DVM, DACVP; Leah A.
• Attach an empty syringe to the needle; break Cohn, DVM, PhD, DACVIM
the seal on the syringe, but expel any air Alternatives and Their EDITORS: Leah A. Cohn, DVM, PhD, DACVIM; Mark S.
before proceeding. Relative Merits Thompson, DVM, DABVP
• If using US or CT guidance, identify the • Bronchoalveolar lavage (pp. 1073 and 1074)
lesion. is more useful for diffuse airway or alveolar

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