Oral Biopsies 2 Flashcards
When are apical lesions submitted into the laboratory as a sample?
following periradicular surgery (apicectomy)
Give examples of periapical lesions that can be submitted for microbiological examination
Most commonly:
* * radicular cysts
* periapical granulomas
Less commonly
* odontogenic cysts present at the apex e.g. nasopalatine duct cysts or odontogenic keratocyst
What is the purpose of fixing excised biopsy material in 10% formalin ?
this is to prevent tissue autolysis from occuring before the sample reaches the laboratory
What is the solution of choice for fixing tissue samples?
10% neutral buffered formalin (a 4% solution of formalin)
What is the problem with submitting apical lesions on gauze placed in formalin solution?
if the volume of formalin is not great enough then the gauze tends to absorb most of the formalin leaving the specimen dry and unfixed
it can also be difficult to seperate the specimen from the gauze
Although it is not essential, what should you courteously inform a pathologist of?
the inclusion of bone in the specimen
Hard tissue (teeth) samples should not be fixed in 10% neutral buffered formalin. True or false
False
They should be fixed in it
Why might a histopathology report for a hard tissue biopsy (tooth tissue) take weeks to come?
this is because decalfcification is required
What does the time for decalcification depend on?
- size of specimen
- consistency of specimen
In what instances is it best to undertake a biopsy in the hospital?
- if there is suspicion of a pre-malignant disease or tumour
- suspicion of widespread mucosal disease
What is the importance of a provisional clinical diagnosis of an oral lesion ?
- can inform or guide the technique and tissue handling that should be used
What should a biopsy to exclude malignancy in a long standing ulcer include ?
the biopsy of the ulcer and some adjacent clinically normal epithelium
What is the benefit of including clinically normal epithelium in the biopsy of a carcinoma?
it allows the coformation that the malignancy arises from the overlying epithelium rather than a deeper structure or a metastasis of a different site
it also allows the invasive front to be examined which can yield useful prognostic information
Why should the centre of large tumours be avoided in biopsies?
this ise because they are often necrotic and will not yield diagnostic material
What is a disadvantage of incisional biopsies of potentially malignant/premalignant lesions?
some studies have demonstrated the presence of cytokeratins in the blood of a few patients following incisional biopsy of an oral SCC
This demonstrates the dissemination of cancer cells which may result in metastasis
What has been suggested to mitigate the risk of blood borne metastasis following incisional biopsies of malignant tumours (including oral cancer) ?
administration of chemotherapeutic drugs prior to biopsy to minimise the risk of metastasis
Why should erosive lesions associated with lichen planus/lichenoid reactions not be biopsied?
this is because erosive areas show non-specific inflammarory changes associated with ulceration and will not be useful in diagnosis
What is the ideal site of biopsy for suspected vesiculobullous disorders?
the ideal site should be adjacent to the bulla where the epithelium is still intact
What samples should a pathology lab receive for a suspected vesiculobullous disorder?
- fresh sample plus (immunofluorescence)
- one that has been fixed in formalin
What is the ideal site of biopsy for desquamative gingivitis ?
intact area of mucosa which is often the attached gingiva
How would you go about the biopsy for desquamative gingivitis?
an elliptical area of the mucosa is incised and carefully dissected from the underlying periosteum with a Mithcell’s trimmer
What types of lesions have a higher incidence of dysplasia or malignant transformation?
- erythroplakia
- non-homogenous or speckled leukoplakia
Give an example of a method that can be used to prevent crush artefacts in biopsied tissue
- placing a suture within the mucosa (e.g. underneath the lesion) and holding the ends of the suture with artery forceps and tying loose knot above the mucosa
What is the importance of a loose knot being placed as opposed to a tight knot being placed when placing a suture before undertaking a biopsy?
a tight knot too close to the specimen may result in crushed tissue
What is the benefit of placing a suture before undertaking a biopsy?
- provision of traction
- prevent unwanted movement of tissue when taking biopsy from mobile structures such as the tongue
- can help pathologist orientate the biopsy sample for sectioning (if a diagram is provided on the pathology form)
When using the traditional technique for tissue handling, what must you ensure?
- [traditional technique is the use of tissue forceps]
- the area that is grasped using the tissue forcep must be away from the site of interest
A punch biopsy is an alternative to ________ biopsies
incisional
Briefly describe the punch used for punch biopsies
- consists of a circular blade attached to a plastic handle
- diameter of the circular blade ranges from 2-10 mm
How can the base of a punch biospy be released?
- simply and atraumatically using curved scissors
or - specimen can be lifted from the mucosal surface and the base undermined with a scalpel
What is the current benefit of punch biopsies over incisional biopsies ?
- fewer artefacts than conventional incisional biopsies
- however, it can be argued that placing a suture in incisional biopsies would also produce minimal artefacts
Why is it safer to use larger diameter punches ?
- avoids handling problems both clinically and in the laboratory