Tissue Sampling, Specimen Handling, and Chromoendoscopy

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Chapter 5 Tissue Sampling, Specimen Handling, and Chromoendoscopy

Biopsy

Pinch Biopsy Forceps

Larger Capacity Forceps

The large-cup (“jumbo” or “max capacity”) forceps requires a large channel, a so-called therapeutic endoscope (biopsy channel 3.6 to 3.7 mm). Some newer designs are intended to provide larger biopsy specimens with the conventional 2.8-mm channels and intermediate-sized channels such as pediatric colonoscopes.1 Larger capacity biopsy forceps are highly desirable to optimize the diagnostic yield. Part of the reason that only a few endoscopists have used the large-cup forceps is the reluctance to use larger capacity forceps that require the larger channel. There is also a puzzling antipathy toward the use of a larger forceps that obtains superior sized specimens. Studies have been done to show that a larger forceps is unnecessary, as if the larger forceps represented a serious threat or a “ploy.”2

Larger capacity forceps biopsies yield two to three times the surface area but are not generally much deeper (Fig. 5.1).The main objective with biopsy is not to obtain more representative sampling of a whole organ but to enable the histotechnologist to see the biopsy specimens to orient them (see Fig. 5.1). Histotechnologists cannot orient small to tiny specimens. The resultant sections with larger capacity forceps are infinitely superior. Proper orientation during paraffin embedding is impossible with often delivered “fleabite”-sized specimens as part of a group of biopsies in a tissue block.

Orientation for embedding in paraffin is the key to maximizing the diagnostic yield from mucosal biopsies. Orientation with crypts and villi are lined up and not cross cut like a stack of doughnuts. This orientation permits assessment of the amount of lamina propria inflammation, focal lesions such as granulomas, and intraepithelial lymphocytes (especially small bowel). In the colon, oriented sections permit assessment of crypt branching (architectural distortion) for differential diagnosis regarding chronicity and assessment of lesser grades of dysplasia by being able to use crypt architectural disorganization as opposed to only cytologic change in cross-cut sections. Oriented sections are required to maximize the yield for focal lesions.

Biopsy specimens taken with larger capacity forceps usually contain very little submucosa or none at all. It is sometimes difficult to obtain specimens with sufficient submucosa when the objective is to diagnose amyloid or rule out or hunt for vasculitis in submucosal blood vessels.

Cold Snare Biopsy

Cold snare biopsy is advocated instead of hot biopsy to remove diminutive polyps from the colon and submit them all to the pathology laboratory.3 A larger capacity biopsy forceps is just as effective for small polyps. In the absence of a cold snare, cold forceps is still preferable to hot biopsy.3 Fundic gland polyps have a characteristic appearance and location, and cold snare or any kind of snare is not generally required. However, in the case of larger fundic gland polyps, especially in the setting of familial polyposis, removing some may be done to rule out dysplastic change in them. The polyps almost always come off easily without bleeding. If the endoscopist is uncertain that a polyp is fundic gland type, a cautery forceps should be used. The endoscopist should always be prepared to apply a hemostasis technique if bleeding is excessive after a cold snare biopsy. Cold snare biopsy of gastric polyps less than 7 mm to distinguish hyperplastic from adenomatous polyps is useful in the appropriate clinical circumstances.

Improving the Quality of Forceps Pinch Biopsy Specimens

Double Bites

The term double bites refers to taking two specimens with a single pass of the biopsy forceps. With conventional-sized forceps, this double-bite technique often yields a tiny second biopsy specimen, or a “macrocytology” (Fig. 5.2). However, the double-bite technique may be used successfully in the colon in ulcerative colitis biopsy surveillance and in the small bowel using a larger capacity forceps. In the esophagus, the double-bite technique is difficult because of the need for angulation and risk of loss of the first biopsy specimen obtained. In the stomach, the size of the specimens is often so generous with the first pass that there is scant room for a second biopsy.

To perform this technique, after the first biopsy specimen is obtained, the closed forceps is placed with slight pressure on the wall where the next specimen is to be taken and is opened against a bit of wall pressure. This pressure helps prevent the first specimen from falling out into the lumen. After opening the forceps poised to biopsy, a few staccato bursts of suction are applied, and then the forceps is closed quickly to obtain the second specimen. One does not always obtain two biopsy specimens. I usually obtain two specimens about once in three to five times.

6 O’clock Position and Biopsies of Gastroesophageal Junction (Cardia) Lesions

When areas are difficult to get at, rotation of the endoscope to the 6 o’clock position makes it infinitely easier to obtain biopsy specimens and to target more accurately (Fig. 5.3). This position is especially invaluable in biopsy surveillance of Barrett’s esophagus where the 12 o’clock position tends to be ignored for visualization and biopsy targeting. The endoscope is rotated so that what was at 12 o’clock is now at 6 o’clock.

For lesions at the gastroesophageal (GE) junction, it is often invaluable to visualize the area on turnaround in the stomach and target biopsy or endoscopic resection from this perspective (see Fig. 5.3C). This maneuver works only if the patient has a hiatal hernia. After the turnaround is done in the stomach, air insufflation is set on high. The endoscope is advanced by slowly withdrawing until the endoscope tip advances right to the GE junction. In this way, there is end-on visualization of a lesion. Additionally, the endoscope can often be torqued slightly to place the lesion in or near the favored 6 o’clock position (see Fig. 5.3). If torque is required for biopsy positioning, the endoscopy assistant maintains it while the biopsy forceps is targeted to the lesion. In the turnaround position from the stomach, some lesions cannot be accessed despite torquing or twisting.

Tissue Handling

Transferring Biopsy Specimens from Forceps to Fixative

The best way to remove biopsy specimens from the forceps is to use a blunt probe to push the specimen out from the base of the opened forceps cups. If one pushes the specimen out by pressing it from the top of the opened forceps or picking at it, the specimen becomes squashed.

Shaking biopsy specimens off the forceps into a fixative bottle may traumatize the tissue and cause denudation of the epithelium, especially from the gastric body. Endoscopists who use the shake technique should alert the pathologist to look for detached epithelium in biopsy specimens from different parts of the gastrointestinal (GI) tract and give feedback. Most pathologists are so used to seeing detached epithelium that they assume it is a default feature (norm) from the trauma of the scope or the forceps.

When exudative lesions are biopsied for diagnosis, shaking specimens into the fixative may peel off the exudate that contains the evidence for the presence of organisms, especially Candida and herpes simplex. These organisms reside in the surface exudate or epithelial slough. Cytomegalovirus does not, and it requires biopsy for diagnosis.

Orientation of biopsy specimens on support materials in the endoscopy unit is not required in clinical practice and in inexperienced hands may lead to more tissue trauma. The key to having well-oriented, high-quality biopsy specimens for histologic examination rests with the pathology histotechnologist’s ability and motivation to embed the tissue “on its edge” in paraffin and obtain sections through the central core of the specimens.6 That depends on providing the histotechnologist with specimens of adequate size.

Polyps: Identifying the Stalk Region

When snare polypectomy is used for the removal of pedunculated or sessile polyps, the key part of the specimen for cancer diagnosis is in the stalk region or the base in the case of sessile polyps (Fig. 5.5). Stalks retract right after removal of the polyp and often shrink further and disappear after fixation. The best way to identify the stalk is to impale it with a short (1-inch) 25-gauge needle, right to the hub with the needle point emerging at the most convex part of the tip of the polyp (see Fig. 5.5). An alternative is to ink the polyp stalk after removal. After fixation for a few hours, the polyp is bisected with a scalpel or razor blade in the pathology laboratory. The two bisected halves are embedded facedown, and this way the first sections to come off are those that show the stalk region in its best orientation.6 Larger specimens should go right to the pathology laboratory to be assessed as gross specimens.