PRINCIPILES OF BIOPSY
Biopsy is the removal of tissue from a .ltvlng individual for diagnostic. exammanon. It is the least equivocal (most : diagnostic) of all the diagnostic procedures performed in the Iaboratory and should be carried out whenever a _definitive diagnosis cannot be obtained using less invasive diagnostic modalities. The four major types of biopsy in and around the oral cavity are (1) cytology, (2) aspiration biopsy, (3) Incisioaal biopsy, and (4) excisional biopsy.
Two main forms of oral cytology can be used in clinical .practlce=-dtffertng in the method of cellular collection ‘.’ and in diagnosis: .~he firstis exfoliative cytologic examination for tumor cells, which was first described as a diagnostic procedure for detection of uterine cervical malignancy. Although application to the oral cavity has been
advocated, it should be used as an adjunct to, not a substitute
for, .incisiona or excislonal biopsy. Studies have ._shown exfoliative oral cytology to be unreliable u.c., having an-unacceptable number of.false negatives) .•..~p<,:ual- Iy when pathologists who lack expertise In oral c;yWlo.gy•· examine the specimen.
Technique of oral brush cytology. The brush, is placed in contact with oraleptthellum and rotated with firm pressure 5 to 10 times (Fig. 21-5; B). Properly perfoIllied, the brush collects cells from all three layers of the
epithelium: (1) the basal; (~) intermediate, and (3) superficial layers. The cellular, material collected on the brush is transferred .to a glass slide and flooded with fixative- (Fig. 21-0, C); After the slide is dry, it is sent to a Special laboratory where the specimen is evaluated by both a
.computer system and a pathologist to first determine that ‘the biopsy brush has penetrated to the basement membrane. If the biopsy has’ 09t collected cells .from the full thickness of the epithelium, the dentist will be.informed that the sample was inadequate for analysis. The brush
cytology should then be repeated.
Aspiration biopsy is the use of a needle and syringe to penetrate a lesion for aspiration of its contents. Two main types of aspiration biopsy are used in clinical practice: l’he first is used only to determine whether or not a reston contains fluid or air; the second is used to remove cellular material
for diagnostic examination by a pathologist. The latter technique is usually performed by a pathologist trained in the technique of fine needle aspiration (FNA). Patients are frequently referred to pathologists for FNA when a soft tissue mass is detected below the surface of the skin or mucosa
during clinical examination. The pathologist uses a special – syringe and needle to enter the mass and collect cells for histologic examination. Neck masses can be reliably diagnosed using this technique. Because deep masses are difficult to biopsy, FNAbiopsy is a very powerful tool.
Aspiration of a lesion to determine whether or not it contains fluid is done routinely before opening into radiolucent lesions of the jaws. Inability to aspirate fluid or air indicates that the mass is probably solid. Aspiration
of a /Ieston can yield extremely valuable information about its nature. A radiolucent lesion .in- the jaw that yields straw-colored fluid on aspiration ‘is most likely a cystic lesion. If pus is aspirated, an inflammatory or infectious process should be considered (i.e., abscess). Air on
aspiration may indicate that a traumatic bone cavity has been entered. Blood on aspiration could represent several sions, themost important of which is a vascular malformation in the jaw. However, other vascular lesions may produce blood on aspiration. Aneurysmal bone
cysts, central giant cell granulomas, and other lesions can produce a bloody aspirate. A fluctuant mass in the soft tissues should .also be aspirated to determine its contents before definitive treatment. Any radiolucency in the bone of the jaws should be aspirated before surgical intervention to rule out a vascular lesion that could result in Iifethreateni g
hemorrhage if incised. Material obtained by aspiration can be submitted for pathologic examination, chemical analysis, or microbiologic culturing.
An incisional bIopsy .is a biopsy that samples only a particular or representative part of the lesion. If the lesion is large or has different characteristics at different locations, more than one area of the lesion may .require sampling. Indications. If the area under investigation appears
difficult to excise because of its extensive size (i.e., larger than 1 ern in diameter), hazardous location’, or whenever the clirtician suspects malignancy, incisional biopsy is indicated.
An excisional biopsy implies removal of the entire lesion at the time the surgical diagnostic procedure is performed. A perimeter of normal tissue surrounding the lesion is also excised to ensure total removal. The entire
lesion made available for pathologic examination, and complete excision may constitute definitive treatment. Indications. Excisional biopsy should be used with smaller lesions (less than 1 cm in diameter) that on clinical
examination appear to be benign. Any lesion that can be removed completely without mutilating the patient is best treated by excisional biopsy. Pigmented and small vascular lesions should also be removed in
their entirety. Principles. The entire lesion, along with 2 to 3 mrn of
normal-appearing surrounding tissue, is excised.