Biopsy handout

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Biopsy handout

Post by Shadi Jarrar on 2/8/2011, 11:51 pm

بسم الله الرحمن الرحيم

4shared.com Biopsy_5_handout.html

Lecture 5

INVESTIGATIONS

A wide variety of investigations are available. Those most frequently utilised in oral medicine are radiology, haematology, biochemistry, immunology, microbiology and histopathology. Other specialized tests may be used, for example those of salivary gland function, which include flow rate studies, biopsy, sialography and scintiscanning.

It is important that the patient be informed of the reason for special tests and investigations, and when several are required these should be planned carefully in order to minimise inconvenience to the patient.


BIOPSY

Biopsy is the examination of tissues removed from the living body for the purpose of diagnosis. There must be clearly understood reasons for removing tissue from a patient. These may be:

1) For definitive diagnosis when a lesion persists after removal of obvious causes or where the clinical diagnosis is unclear or needs confirmation

2) To determine prognosis

3) To delineate the boundaries of the lesion and affected tissues

4) To assess any changes in a chronic lesion or recurrence in a treated lesion

5) The microscope slide and report form a permanent record which is useful for subsequent management, clinical research and teaching








Criteria for success:

1) The site must be characteristic of the lesion, which will be its most active part

2) The depth of tissue removed must be adequate and even to assess the extent of the lesion

3) The area removed should be sufficient to allow for orientation, shrinkage of the specimen and for an adequate number of sections, bearing in mind subsequent healing

4) Normal adjacent tissue should be included for comparison to show the transition zone and to enable the pathologist to assess completeness of removal

5) The labelling must be clear and appropriate clinical information should be supplied

6) The tissue should be fixed straight away



When to take a biopsy:

Observation periods are of little diagnostic value for long standing red or white mucosal lesions or ulcers for which there are no obvious causes, in all unusual lesions and when malignancy is suspected, for instance by rapid growth, biopsy without delay is essential. In speckled lesions, avoid thickly keratinised areas and choose instead thin, atrophic mucosa; a large lesion with varying characteristics may need more than one biopsy to ensure representative samples.







Types of biopsy

1-Incisional

It is the removal of only a portion of the lesion, usually with adjacent normal tissue, exclusively for the purpose of diagnosis, generally before the definitive therapy is started.

Punch biopsy may be used to obtain tissue from an inaccessible area, or where incisional biopsy is not practical or when multiple samples from an extensive lesion are required. For this, a special instrument which removes a small fragment or core of tissue is employed.



2- Excisional

It is a similar technique to incisional biopsy. Excisional biopsies are both diagnostic and therapeutic as they remove an entire lesion with a peripheral border of normal tissue. This is used for lesions which are recognised clinically as benign, small and easily removed. Thus, whenever feasible, this technique is preferred to incisional biopsy.



3- Fine needle aspiration cytology

It is a straight forward and minor procedure performed under infiltration type local analgesia, using a wide bore needle. The technique differentiates solid or vascular lesions from cysts which present as a central radiolucency in bone; such lesions should always be aspirated to avoid a mistaken biopsy or operation. For example, a central giant-cell granuloma of bone might have been mistaken for a dentigerous cyst. Other examples of its use would be





the differentiation of a cyst from the neighbouring maxillary antrum. Aspiration of any lesion thought to be a haemangioma is essential to avoid misguided operation. In addition, analysis of the aspirated fluid may prove helpful by showing cholesterol crystals, or the presence of keratinised squamous cells or a low protein concentration.



4- Drill biopsy (for hard tissue lesions)

It is a technique used to obtain hard tissue specimens from central bone lesions; it is a minor procedure done under local analgesia, but rarely used now since lesions are either followed up clinically or specimens are taken during operative treatment. A mucoperiosteal flap is raised to allow access of an Ellis biopsy drill in a straight hand piece, which removes cylindrical specimens of 1.4mm in diameters to any required depth. To avoid overheating bone, the drill should be run slowly and irrigated well.



5- Exfoliative cytology (smear)

It is a technique in which individual cells are curetted from the surface of a lesion for examination under a microscope. It is regarded as an adjunct to biopsy and not as a substitute. Select an area, wipe away excessive saliva, debris and any sloughs, and scrape the surface of the lesion firmly with a wooden spatula, softened if necessary in water; alternatively use a flat metal or plastic spatula, but try to avoid haemorrhage. Scraping the fissures of a keratinised lesion will obtain more representative basal cells. Spread the material obtained evenly on a glass slide; material spread too thickly



makes overlapping cells hard to interpret, and when spread too thinly makes examination of the sparse material unrewarding. The smears are fixed immediately to avoid dehydration and distortion of cells, a mixture of equal parts of ether and 95% ethanol acting for at least fifteen minutes is used, or a spray fixative; alternatively, they may be air dried. The slides should be kept apart during transport and a diagram of the lesion and the areas sampled is supplied on the pathology form. The technique is useful firstly for lesions where malignancy is suspected; secondly an area treated for malignancy can be observed for a recurrence; thirdly, the most representative area for biopsy can be selected from the large areas of clinically abnormal mucosa. Lastly, it is a useful preliminary procedure for a patient who is unable or unwilling to attend for biopsy within a reasonable interval. It is quick, simple, easily repeated and produces minimum discomfort. It is also used to help diagnose herpes and pemphigus in man, and a similar technique can be used to detect candidal hyphae. Wherever the result of a smear is not clear it should be repeated or a biopsy performed.



Technique for mucosal biopsies

1- Cleanse site with sterile gauze

2- Wherever possible, incisional mucosal biopsy specimens should be taken from the margin of the lesion and include adjacent normal tissue (see Fig.1). The specimen should never be taken centrally within an ulcer base, or from eroded or necrotic areas. Although a representative portion of the lesion is desired, adequate access to that area may be a limiting factor.

3- The method of anaesthesia administration can occasionally be significant. In most cases, local infiltration is adequate, provided that the injection is made adjacent or deep to the biopsy site rather than immediately within site to avoid distortion. Alternatively, regional nerve block may be used.

As little local anaesthetic solution as possible is given by infiltration, and added vasoconstrictor, if not contraindicated, assists homeostasis (2% lidocaine + 1:100,000 epinephrine is the preferred anaesthetic). More vascular tissue as in the tongue may require the use of lidocaine with 1:50,000 epinephrine; however, this is of questionable benefit in the control of homeostasis. In patients for whom epinephrine is contraindicated, excessive haemorrhage is uncommon when 3% mepivacaine, a non-vasoconstrictor containing local anaesthetic, is used. Injectable diphenhydramine is an acceptable alternative for patients sensitive to lidocaine.

4- Oral mucosa has several underlying supporting structures. The labial and buccal mucosa is the easiest area in which to perform a biopsy as the fingers can provide external support for the tissue. The tongue is best managed by a firm grip adjacent to the biopsy site. Fixed mucosa can be easily incised to the periosteum.

5-Use semi-elliptical incision to provide adequate sized biopsy (at least 1.0 x 0.5 cm) and to include margin of normal tissue

6-The handling of the specimen is critical in the biopsy technique. The use of atraumatic (tissue forceps or Adson’s forceps) with serrated tips is preferred. Mouse-toothed forceps, while providing a more secure grasp on the specimen, frequently induce artefacts by punching holes through the tissue, which interfere with definitive histopathologic interpretation. Alternatively, when the corner of the specimen has been raised, it may be carefully handled with tweezers at one point away from the lesion. If a suture is used it also serve to orientates the specimen. Insert fine holding suture to anchor tissue to be excised. This eliminates risk of losing biopsy with suction, it also removes temptation to grip tissue with forceps and thus damage the cells

7- The tissue edges should be undermined, the base of the tissue core can be released using either a no 15 scalpel blade or fine, curved iris scissors. Movable mucosa on the cheeks and lips can frequently be everted, the base of the tissue core released with iris scissors. Fixed mucosa is more amenable to secondary incision with a no. 15 scalpel blade. Homeostasis achieved before closure

8- When the specimen has been removed from the mouth, it should be mounted, epithelium-side down, on a small piece of blotting paper and immersed immediately in a fixative. Saliva and surgical haemorrhage make the specimen stick to the paper. When the specimen and paper are placed in fixative, the specimen will not distort, thus aiding the pathologist in proper orientation of the specimen

9- Unless required for frozen sections, immediately immerse in 10% formaldehyde solution. Methylated spirit is permissible but state nature of the fixative on the request form. Do not use water or saline.

10- Sutures should be inserted without tension, otherwise a whitehead’s or an Iodoform dressing may be sutured to cover the wound, make appointment for 5 to 10 days

11- Send specimen, adequately packed and labelled, to an oral pathology department with details of patient and lesion. Include as a minimum; name, age & sex of patient; site of lesion (draw or use diagram if provided);

duration of lesion; essential clinical findings; results of investigations (send radiographs with any tissue from jaw lesions); previous treatment (including biopsies); clinical differential diagnosis.

12- Allow 1 week for histopathology report on routine soft-tissue lesions, longer if they contain bone. If a more rapid result is required write URGENT on the laboratory request form and preferably also telephone the laboratory to give other relevant information

13-Postoperative instructions include an admonition against inadvertent trauma to the area, either by diet or through attempts at oral hygiene, for 48 hours. Patients are also cautioned that the saliva may appear slightly blood-tinged during the first 24 hours. Warm salt water rinses are recommended for palliation. Acetaminophen or non-steroidal anti-inflammatory agents are the preferred analgesics for occasional postoperative discomfort



Precautions

1- Risk of haemorrhage due to local and systemic factors

2- Risk of dissemination of neoplastic cells (e.g. pleomorphic salivary adenoma, ameloblastoma); always a theoretical problem but the priority is to obtain an accurate diagnosis

3- Do not crush, distort dry or otherwise abuse the biopsy; leave suture in position



Fresh tissue for frozen sections is required for:

a) Rapid diagnosis (within minutes)

b) Special techniques e.g. immunofluorescence or immunoperoxidase techniques.

Patient’s serum may be required also when a frozen biopsy is anticipated, contact the oral pathology laboratory as early as possible on the same day. The tissue can then be transported to the laboratory in liquid nitrogen or if, not available, use a piece of gauze soaked in water to hold the specimen and take it immediately to the laboratory as delay can lead to serious tissue deterioration. Usually, half of the original biopsy is stored frozen, the remainder being fixed as usual.



After surgery

As mentioned above, all specimens should be labelled with the patient’s name, initials and identification number, and the completed form should clearly convey the essential details shown on this slide since this is the pathologist’s sole source of information about the patient. Before reaching the pathologist for reporting, the fixed specimen will be cut, embedded, sectioned and stained.

When malignancy is expected the clinician should mark the form URGENT and add his T.N.M. grading. This is a clinical assessment of the extent of malignant lesions by physical examination of the patient. The letters T.N.M. stand for the descriptive category of any tumour, node or metastasis. The disadvantages of biopsies are that specimens from non-representative areas may fail to confirm the clinical diagnosis. Also, the biopsy may be an additional procedure since any treatment must follow the diagnosis, and the procedure may disseminate malignant cells. This is a theoretical objection and one usually raised against incisional biopsy of a suspected malignant melanoma. However, if bone lies beneath the lesion which is thought to be malignant, periosteum should not be penetrated. Thus, histolgical diagnosis will always attempt to correlate with the clinical findings, and is essential in malignant disease. Remember that from a firm diagnosis come the benefits of well planned treatment and that histology is but one piece of evidence, the clinician must finally decide management






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Shadi Jarrar
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تاريخ التسجيل : 2009-08-28
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الموقع : Amman-Jordan

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