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Patient Prep: For superficial aspirates, clean technique suffices for cleansing of the skin surface. Local anesthetic may or may not be used. If more than two or three attempts are anticipated, anesthetic is recommended. However, be certain not to contaminate the lesion with a large volume of anesthetic. Also, make attempts not to directly interfere with the ability to palpate and localize the lesion. For deep aspirates, sterile technique is required for cleansing of the skin, and local anesthetic is usually required.
Fine needle aspiration of mass lesions is commonly utilized in the detection and characterization of a variety of malignant diseases. Obtaining an adequate specimen requires attention to good aspiration technique as well as processing of material obtained. It is highly desirable that several direct smears be prepared (preferably air-dried) for all fine needle aspiration specimens submitted to Cytopathology.
Indications: To determine benignity or malignancy of mass lesions, and to characterize the type of malignancy or benign disease, which is present.
Collect: FNA Specimens
Specimen Required: Adequate cellular material for cytologic evaluation obtained from an appropriately performed fine needle aspiration. This will depend on the specimen site and character of the lesion being aspirated. In general, this requires that there be enough material for the examiner to at least determine that the aspirating needle sampled a mass lesion.
Supplies: 10 mL syringe. Syringe pistol (optional). 23 to 27 gauge needle of appropriate length. Single-end frosted glass slides labeled with the patient's first and last name, date of birth, and specimen source (for preparation of direct smears). Fixative (either Saccomanno fixative or 95% ethyl alcohol).
Collection Procedure: Please note that the following collection procedure is a suggested guideline. Aspiration techniques vary widely based on personal preferences, and specific clinical circumstances must be taken into account when deciding on the method of aspiration utilized.
Identification and Localization of a Mass Lesion
Mass lesions usually come to attention either by simple identification of the development of a mass (usually superficially) or by the development of symptoms directly or indirectly caused by the mass. In order to be able to sample the identified lesion, some means of accurate localization must be available. If the mass is superficial, simple isolation of the mass between the thumb and index finger of the nonaspirating hand is usually sufficient. For deeper masses, ultrasound or radiographic techniques are usually required for accurate guidance and localization of the aspirating needle.
Aspiration (Superficial Masses)
Assemble the aspirating equipment. If direct smears are to be made, label the slides prior to the aspiration. With the target of aspiration fixed with the nondominant hand between the thumb and index finger, and the syringe or syringe pistol in the dominant hand, the needle is placed against the skin. If the lesion is very superficial, the needle should approach the skin at approximately a 30-degree angle. If the mass is deep, it should approach the skin at a perpendicular angle. A quick motion should be used in passing the needle through the skin. The needle is then advanced through the subcutaneous tissue into the mass. If the mass is small, the needle should be aimed toward the center; if it is large, the needle should be aimed toward the periphery, as the center of larger masses may be necrotic. A noticeable difference in the consistency of the tissue should be noted when the needle penetrates the mass. With the needle in the mass, the needle tip should be moved in short motions, initially, to loosen cells within the mass. Negative pressure is then applied by pulling back on the plunger of the syringe. When blood or material appears in the hub of the needle, the aspiration should be stopped. Prior to withdrawal of the needle, negative pressure must be released to prevent suction of the material into the barrel of the syringe when the needle exits the skin.
Aspiration (Deep Lesions)
While the basic aspiration procedure is similar for deep lesions, specialized equipment for imaging, specialized needles and set-ups for aspiration, and emergency equipment for handling major complications are required. Specific techniques are highly variable, according to personal preferences.
Preparation of Direct Smears
For preparation of smears, single-end frosted slides should be utilized. Slides should be labeled with patient's first and last name, date of birth, and specimen source in pencil prior to aspiration. Some author investigators recommend gently expressing a drop of aspirated fluid onto a slide, while others recommend forcefully expelling the material onto the slide. The actual method will be determined in part by the nature of the material present. If the aspirated material is abundant and fluid, a drop may be easily expressed without force. If the material is scant or more viscous or solid, the material must often be forcefully expelled. The latter method can result in splattering of material off of the slide, and will utilize most of the specimen in the preparation of a minimal number of smears, necessitating more passes if additional material is required for additional studies. The former method allows for better control of the smear process.
Once the specimen is on the slide, it must be smeared. The simplest way to accomplish this is to oppose a second glass slide onto the first, allowing the aspirated material to provide surface tension between the two slides, and then gently and quickly pulling the two slides apart in a horizontal motion to distribute the material in a thin film over both slides.
The smears should be: 1) immediately fixed in either Saccomanno fixative or 95% ethyl alcohol for Papanicolaou staining (delineate with an "F" on the frosted end of the slide) or 2) air-dried for Diff-Quick staining (delineate with an "A" on the frosted end of the slide).
If material remains in the hub of the needle, additional smears may be prepared or the material may be rinsed into a tube containing either fixative (CytoRich™ Red, CytoLyt, Saccomanno, etc.) or a physiologic solution such as normal saline, or RPMI. If smears are not prepared, all of the aspirated material should be flushed into a physiologic solution.
Submit the specimen (smears and/or material rinsed into solution) to the Cytopathology Laboratory along with the completed Cytology test request form. If transport of specimen in fluid will be delayed more than 24 hours, the specimen should be submitted in fixative. If transport time of fluid specimen will be less than 24 hours, or fixative is not available, the specimen should be refrigerated or kept on wet ice until transport to the lab.
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