Role of the Pathologist Flashcards
What is the role of the pathologist in the MDT for head and neck cancer?
To establish the diagnosis of cancer – subtype, grade
Outline the anatomic extent of the tumour – completeness of excision
Identify other prognostic factors – may include molecular markers
Final staging of the disease (pTNM) – in relation to need for further treatment
What is done when specimen arrives in pathology department?
The request form is checked
– patient details all present
– the form and path pot match
– Tracking system
Fixed in formaldehyde for at least 24 hours
Specimen photograph as appropriate
What is the function of formalin?
Stops enzyme activity of cells, don’t undergo necrosis (still see outline and nuceli clearly)
What information is recorded about the specimen itself?
- Height
- Width
- Location
- Colour
- Description
What is done once surgical margins are identified?
Painted in black
-> Helps pathologist determine whether cells on periphery are involved in malignancy or are clear
What is the primary tumour broken into?
Blocks
-> small pieces around 5 mm thick are chosen
What do the pale areas in the bulk of tissue block represent?
Extent of tumour
-> If area close to margin it could suggest it is involved
What is the purpose of a retinal node biopsy?
identifies presence of micro-metastases within main draining LN from area with suspected malignancy
What is done with pieces of tissue chosen of analysis
Put onto cassette- Can be metal or ceramic
-> Has patient detail and numbers
Tissue are treated with alcohol, dehydrated, other chemical to remove fat
Tissues can be impregnated with wax (this allows cutting of thin sections of tissue)
->Now done automatically by machine
What are pieces of biopsy not used kept for?
Forensic requirements
Future technology advances
How are blocks sliced into specimens that can be used for histology assessment?
Using microtome
-> slices are 2-3mm
What is done to wax specimens so they can be studied histologically?
Wax is put in water bath- smooths out
Placed on glass slide
Put in a machine which puts H and E stain on it
Covered in plastic
Delivered to reporting room- studied and report carried out
Why is any malignancy reported to the royal college of pathologists
Important for statistics- amount of cases in a year
To see if certain malignancy are increasing and to see if there is a reason (diet etc)
What is included in the dataset sheet filled out by pathologist?
- Core info- patient and centres
- Quote TNM stage
- If patient has previous radio or chemo
- Type of specimen
- Site
- Diagnosis- subset
- Note differentiation (affects prognosis)
- Invasive front- if non-cohesive (indicates involvement of LNs)
- Diameter
- Maximum depth of invasion
- Distance to mucosal margin (if <1mm from surgical margin- margin is likely involved and malignant cells are present in area)
- Note any metastases
- Dysplasia in epithelium
What is good about a well differentiated tumour?
Responds better to radio/chemo, less likely to recur, better prognosis
What is considered clear margins?
if malignant cells >5mm from margin
Where do majority of oral cancers arise from in UK?
Clinically normal mucosa (not PMLs)
What molecular marker assessments may be carried out?
HPV-oropharyngeal tumours
Future genome sequencing- aids in diagnosis and precision treatment i.e monoclonal antibodies (targeted)
Immunohistochemistry
Special stains
-> PAS- Candida albicans
-> cell adhesion molecules
-> evidence of angiogenesis
What does pathologist use to reach diagnosis?
- Clinical findings
- Light microscope
- Special tests
- PAS stain- candida albicans (if chronic hyperplastic candidiasis), mucous cells
What is the field change theory?
Most parts of oral cavity are likely to be affected by genetic changes due to presence of malignancy
What are frozen section used for?
- Done intra-operatively
- Tissue is put in cryo-stat
- -25 degrees
- After 15-20 mins is available for viewing
- Does not show fine detail- but can help clinician decide whether margins are clear or identify a neoplasm initially
