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The Thin-needle Aspiration Method
Thin needles, 0.6–
by ophthalmologists using a 30-gauge needle to obtain a very small sample that is useful for diagnosing metastatic or primary neoplasms within the eye.37 With the continued growth of fine-needle aspiration biopsy,there have been some variations in needle design. The Franseen needle has a notched tip and stylus, which in practice seems to provide both semisolid material for smears and sometimes predominantly thin microcores of tissue. These microcores, whatever style of needle provides them, should be rolled onto the slide surface to obtain smears for initial staining and examination.
They should not be crushed between two slides in an allout effort to produce smears.
The Milex and INRAD needles were designed to improve sampling from firm fibrous breast masses. They both have a slot on the side and are referred to as side-port needles. While the side-slotted needles procure a greater volume of aspirate they also produce much more discomfort during aspiration. The author does not use them for that reason. Use of a small amount of local anesthetic may be indicated when aspirating with the side-port needles.
Radiologists most often use the
Microcore needle biopsy for both palpable and non-palpable breast lesions has largely supplanted fine-needle aspiration biopsy, though controversy over which method remains.
In medical centers that specialize in diagnosis and treatment of bone and soft tissue tumors, core needle biopsy is often combined with FNA. 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 tissue 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 aspiration biopsy.
Cell Block Preparation
Cytoblock Cell Block Preparation System, available from Themo Fisher Scientific; website: http://www.fishersci.com/
Kit includes:
Cytoblock cassettes
Cytoblock reagent 1 (clear fluid)
Cytoblock reagent 2 (colored fluid)
1. Record patient information on the cytoblock.
2. Use samples previously fixed in neutral buffered formalin.
3. Concentrate the fixed cells by centrifuging the sample for several minutes. Pour off the excess fluid and drain the tube on a paper towel.
4. Estimate the amount of sample present. If the total amount of sample is 2 drops or less, add 4 drops of reagent 2 to the specimen pellet and mix with a vortex motion.
5. If the sample is more than two drops, divide into several cell blocks based on 2 drops per block. For example, if there is 4 drops of sample (enough for two cytoblocks), add 8 drops of reagent 2 and mix with a vortex motion.
6. Assemble cytoblock cassettes into cytoclip (cytospin standard equipment) and keep horizontal. The locating peg on the back of the cytoblock cassette fits into the hole in the cytoclip to be properly oriented.
7. Add 3 drops of reagent 1 into the center of the well in the board insert. Reagent 1 should coat the entire circumference of the well in the board insert. Use care to avoid getting any reagent 1 on the top surface of the board insert.
8. With the backing paper projecting toward the top of the cytoclip, place a cytofunnel (cytospin equipment) disposable chamber over the prepared cytoblock and secure the metal clip holder in the usual manner. (See cytospin operating instructions.)
9. Place the assembled cytoclip into the cytospin rotor.
10. Place the mixed cell suspension in each cytofunnel.
11. Close the cytospin and set for 5 minutes at 1500 rpm. Use the low acceleration setting. Start the cytospin.
12. When the cytospin stops, remove the cytofunnel assemblies and place horizontally. Release the clip and remove the funnels. Removal may require rocking the funnel to the side to separate the funnel assembly from the underlying board insert. Be certain the cell button is in the well and has not adhered to the funnel. Then discard the funnel.
13. Place 1 drop of reagent
14. After processing in the standard tissue processor, open the cytoblock cassette. Fold back paper and remove the board insert. Use fine forceps inserted through holes under the board insert.
15. Dislodge the cell button into the base mold and embed flat. Discard the board insert and backing paper.
16. Reclose the cytoblock cassette and place flat side up (round peg side down) on top of base mold. Fill with paraffin.
17. Handle as any paraffin block, but trim carefully because cell buttons may be quite thin.
Reference
Bibbo M, Wilbur DC. Comprehensive Cytopathology
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