Biopsy and Cytology, Physical and Chemical Injuries Flashcards
What is oral biopsy about?
Accurate diagnosis and treatment of oral disease is a fundamental component of the patient’s comprehensive dental carea nd the base of high-quality dentistry.
Although clinical and radiographic findings may provide sufficient information for the diagnosis of some conditions, many oral diseases or conditions require additional information.
This additional information may be provided by biopsy, to make a definitive diagnosis.
When the clinician recognized an abnormality, he/she must first attempt to determine the etiology.
If there is evidence of trauma, the clinician may provide treatment e.g. smooth rough tooth’s surfaces and may re-evaluate the lesion for a period of 1-2 weeks to monitor resolution.
If there are sign and symptoms of infection, (e.g. candidiasis or herpes simplex), and clinical history information may provide the clincian with enough information to arrive at a tentative clinical diagnosis
In the case that the clinician determines the lesion to be a self-healing and not needing any treatment, follow-up is required to insure normal healing.
After a 2-week period, any remaining lesion that does not respond to the conventional therapy is indicated for biopsy!!
Submission of removed tissues to a pathology laboratory for a diagnostic examination constitutes a generally accepted standard of patient care.
What is a biopsy?
A biopsy may be defined as the removal of a representative section of a living tissue from a lesion for microscopic examination.
There are general guidelines for doing a biopsy, which are flexible depending on individual circumstances.
In all cases whether biopsy is performed or not, documentaiton of the lesion and follow-up are absolutely necessary.
As a general rule, any tissue removed from a living person should be submitted for microscopic examination.
what does submission of removed tissue to a pathology lab give you the opportunity to do?
Establish a definitive diagnosis
Confirm a provisional clinical diagnosis
Provide additional information in instances where there is no clinically evident cause for a lesion, or when there is no resolution after appropriate, conservative treatment.
Determine whether a neoplastic process is benign or malignant (type, grade, stage, treatment, prognosis)
Establish the adequacy of surgical margins
Provide diagnostic information to the clinician for management of disease.
The oral and maxillofacial pathologist is the professional, who evaluates the oral biopsy tissues.
An adequate tissue sample is critical when obtaining a biopsy. There are several ways to obtain tissue samples for microscopic evaluation. Excisional and incisional biopsies are the most commonly used techniques for the diagnosis of oral lesions.
what is the difference between excisional and incisional biopsies?
Excisional biopsy: removal of the entire clinical lesion.
- this is most appropriate for small, accessible lesions.
Incisional biopsy: sample only a portion of the lesion to establish a diagnosis prior to the treatment.
- this is more appropriate for large lesions, and suspected autoimmune or mucocutaneous conditions, where tissue samples should be submitted for routine histopathologic examination as well as direct immunofluorescence studies.
It is very important to indicate to the oral pathologist whether an excisional or incisional biopsy was performed because this affects the method of handling tissue.
For example, a lesion, which is suspected of being malignant and is totally excised, will be inked. Its surgical margins will be evaluated microscopically to determine if the lesion was totally removed.
Knowledge gained through histopathologic examination is useful in estimating clinical behavior and prognosis of disease, and assessing the need for any additional therapy and follow-up evaluation.
Although histological study is one of the most valuable means of diagnosis pathology, it has its limitations.
Sometiems no definitive diagnosis can be made. The histopathologic features may only suggest a diagnosis or may be entirely non-specific
The histological features can be altered by topical medications applied over the area in question e.g. topic steroids.
When the histological picture is not diagnostic, correlation of the histology with the clinical findings, “Clinico-pathologic correlation,” frequently makes a diagnosis possible.
What size should the biopsy be?
The specimen should be no smaller than 3mm in any dimension.
Specimens that are too small (less than 3x3x3mm), or of inadequate depth may be insufficient for accurate microscopic interpretation.
Additionally if the specimen is too small is often difficult to orient properly for sectioning and mountin the sample on a slide.
A mucosal biopsy should include the epithelium with a portion of the underlying connective tissue.
If the lesion is less than 1cm, it may be totally removed.
If the lesion is greater than 1 cm (e.g. 3cm), an incisional biopsy may be the technique of choice.
what should be the appearance of the area you are biospying?
choose themost suspicious areas, including the growing border of the lesion and some normal tissue.
In some cases several specimens are necessary.
what is an adequate sample for biopsy?
fragmented specimen often create difiiculties for accurate interpretation.
Incisions should be clean and made with sharp blade to prevent tearing and distortion of tissues.
Avoid slough or necrotic areas
IF the lesion is ulcerated, the clinicians should obtain a portion of the adjacent intact epithelium in the specimen.
Give local or regional anesthesia but not into the lesion
Never open, incise or divide the specimen, always send it intact
IF YOU CAUTERIZE THERE IS AN ARTIFACT IF YOU DO THAT.
Handle the sepcimen gently to avoid a crush artifact, suctioning artifact, forceps squeeze artifact, cauterization artifact, freezing artifact or distortion.
Heat produced by laser and electrocautery often distorts the tissue, making diagnosis difficult
For flat mucosal lesions, slight drying on the cut surface on a piece of paper will prevent the specimen from curling up when it is put into the formalin
Autolysis occurs rapidly; therefore it is essential that the tissue be placed in the fixative 10% formalin immediately..
Clinicians may want to know if a lesion has been adequatley excised by indicating orientation margins with long and short sutures.
What should you do for anesthesia when taking a biopsy?
When possible, block anesthesia should be used rather than infiltration, which may distort the microscopic anatomy.
What should you due for immunofluorescence studies for biopsy?
Mucocutaneous diseases, require for diagnosis the use of both, light microscopic examination and immunofluorescence (IF) studies.
- Important, the tissue sample for IF should be taken peri-lesional tissue, with abundant epithelium. If the epithelium is lacking or separated from the connective tissue, the interpretation and diagnosis are impossible.
The specimen for light microscope should be placed in the fixative 10% formalin.
The specimen for IF should be submitted in a special transport media called MICHEL’S solution. As soon as you remove the tissue sample from the patient, you ahve to place it in Michel’s solution and send it to the lab immediately.
It is also important to remember is that any steroid therpy should be reserved until after the biopsy as pre-surgical steroids use may alter the histopathologic and direct immunofluorescence findings.
What about patient data, lesion information, and history for biopsy?
The importance of patient cannot be overemphasized. This data is essential and can influence the diagnosis and management of the lesion.
You must complete the pathology specimen requisition form thoroughly, accurately and legibly.
The pathologist can give the clinician a maximum amount of information only if every specimen submitted for histological diagnosis is accompanied by detailed an relevant clinical information, including a differential diagnosis.
Provide surgical findings
Diagnostic radiographs are important with dealing with bone lesions.
Quality clinical photographs are very helpful.
What about processing of the specimen for biopsy?
A biopsied lesion for routine light microscopic examnation should be placed in a properly labeled container labelled with two identifiers, patient’s full name, PHR (patient hospitalization record), site of biopsy and date of biopsy in 10% buffered formalin in a volume of at least ten times itself in which to become fixed.
Absolute alcohol tends to dehydrate the specimen producing artifacts.
In the pathology laboratory the specimen is measured, described and trimmed. Then, it goes through a successive graded series of alcohol to be gradually dehydrated. Then, it is cleared with xylene and infiltrated with paraffin; embedded in a block of paraffin; cut to a thickness of 4 microns; placed on a glass slide and then stained.
The routine stain is hematoxylin and eosin (H&E).
Althought routine H&E stained sections are essential for diagnosis, auxiliary methods such as special stains, immunohistochemical (IHC) procedures or ultrastructural studies are sometimes indispensable for reaching a definitive diagnosis.
Special stains are so called because they are used on special caes to help facilitate cell or tissue recognition. Only a limited number of these special stains actually improve a diagnosis suggested by routine tissue processing and H&E staining.
The hard tissue specimens such as bone, teeth or stones are decalcified until they are soft enough to section. The length of time varies with the hardness of the tissue and the size of the specimen.
How should a pathology report be read? how about following up?
- READ the pathology report completely
- CHECK the report for correctness in the patient information: name, PHN, etc.
- CHECK if the findings are consistent with the clinical diagnosis and investigations “Clinicopathologic correlation”
- Contact the pathologist if inconsistency.
FOLLOW UP:
- Sometimes re-biopsy may be necessary if the initial biopsy was not representative or diagnosis is unclear or not understood.
- Always do clinical follow-up to ensure normal healing or sometimes to monitor recurrence.
What are possible reasons for failures in histopathology diagnosis?
Specimen is poorly fixed or damage during removal.
Specimen unrepresentative of the lesion or TOO small
Plane of histological section does not include critical features.
The disease does not have diagnostic histological features e.g. aphtous ulcers
The histological features have several possible causes e.g. lichenoid inflammation, granulomatous inflammation.
The histological features are difficult to interpret e.g. a malignant poorly differentiated tumor that its type cannot be determined.
Inflammation may mask the correct diagnosis e.g. Odontogenic keratocyst “OKC” (keratocystic odontogenic tumor) in the presence of inflammatory changes, the typical features of OKC may be altered.
Treatment of lesions before the histopathologic diagnosis e.g. mucocutaneous disorders pre-treated with topical steroids before a histopathologic diagnosis is established may alter the typical histopathologic features.
what is exfoliatve cytology? advantages? disadvantages?
refers to the scraping of cells from the mucosa for microscopic examination
Advantages:
- quick, easy, painless procedure and local anesthetic not required
- special techniques such as immunostaining can be applied with a proper coated slide
Disadvantages:
- A definitive diagnosis is not possible without a biopsy e.g. unreliable for diagnosing cancer.
- All suspicious lesions require biopsy, even with a negative cytology.
It is of no value in hyperkeratotic lesions.
What are common indication for oral cytological smears? what about less common indication?
common - candida infection
less common - herpetic vesicles - in some atypical cases
- white sponge nevus
