Lab Diagnosis Flashcards
What are the types of tissues that can be sent to the histology lab?
Tissue
- diagnostic biopsy including incisional or needle core
- excisional specimen
Cytology
- exfoliative (scraped or shed cells)
- fine-needle aspiration
Examples of cytology samples which are shed? Why is it not great for cancer diagnosis?
Those that fall off a surface
- sputum
- urine
- pleural and ascitic fluids
Cells usually degenerate so cancer pick-up rate is low
What is a scrape?
Examples
Good for cancer diagnosis?
From a surface eg
- cervical smear
- bronchial bushings
Yes - they are intact and viable cells so cancer pick-up rate is higher
When is an aspirate used? When is image guidance needed?
When there is no surface available eg accessible ku o, breast or lymph node
Can have image guidance to help for inaccessible lumps, the liver or pancreas
When processing samples, the tissues a cut up and a macro description is given. What observations does this include?
Tumour size
Appearance
Spread
Why might some tissues be inked?
If it is tissue resected during cancer surgery - demonstrates the excisional margin when looking down a microscope
What is used to support tissue so it can be cut up to 4μm sections? What happens next?
Impregnated with wax
Mounted on a glass slide and stained
What are some problems when trying to diagnose cancers?
Can be difficult to tell if some cases are malignant or benign - on a spectrum
What aspects are normally considered in a histology report?
Lesion present? Is it malignant? Type of malignancy? Grade Stage (spread) Is it all out?
What are the tissue changes that indicate a tumour is malignant?
Dysplasia
Invasio
Infiltrative margin
What cytological changes indicate that a tumour is malignant?
Nuclear pleomorphism - size, shape and staining
Increased proliferation
Abnormal mitotic figures
What are the different histogenic classifications of tumours?
Differentiation
- squamous
- glandular
- lymphoid
- melanocytic
Molecular classification may be more useful in the future eg BRAF mutation
What are the different considerations when considering the type of malignancy?
The differentiation/histogenic class Architectural arrangements eg glands Cytological differentiation
What are the cytological differentiations considered?
Morphology eg desmosomes, mucin, melanin
Protein expression - lymphocyte differentiation pathogens
What aspects are looked at in protein expression?
Filaments - are they low or high molecular weight cytokeratins
Specific protein produces eg thyroglobulin
Enzyme production
What is the gold standard for cancer diagnosis?
Histology
What is assessment of grade based on?
Proliferation
Architectural differentiation
Pleomorphism
What is grade used for?
Prognostication
Management
What is stage used for?
Predictor of prognosis and management
Where do carcinomas and sarcomas spread to/via?
Carcinomas - to lymph nodes
Sarcomas - via blood stream
What does TNM stand for in staging?
Tumour
Nodes
Metastasis
What is wrong with axillary clearance in treating breast cancer?
Has significant morbidity due to lymphoedema
What cancers is sentinel lymph node biopsy commonly used for?
Breast
Melanoma
Penile squamous cell carcinoma
Head and neck squamous cell carcinoma
How is sentinel lymph node biopsy done?
Inject a dye and short half-life isotope
Tumour will reach the first lymph node in the draining site first
Therefore if the lymph node is negative of dye, the patient does not need clearance as it has not spread to the lymph node
What is done in Moh’s micrographic surgery?
A layer of skin is removed each time and assessed under a microscope there and then. Allows for close examination of skin to look for cancer cells
What are some ancillary techniques (supportive) to aid in diagnosis?
Histochemical stains to characterise tissue components such as collagen and melanin Electron microscopy PCR In situ hybridisation Cytogenetics - detect translocations
What is PCR used for in cancer diagnosis?
Assess monoclonality
See if there is an infection eg HHV8 in Kaposi’s sarcoma
How is immunohistochemistry done?
Antibodies bind to specific proteins in tissues
Antibodies are applied to tissue sections and detected via a colour-producing peroxidase reaction
Antigens of interest can be injected into animals to stimulate an immune response
Give some examples of biological markers which can help to determine therapy
Steroid receptors - tamoxifen
HER-2 - Herceptin
C-KIT expression - imatinib
CD-20 expression - rituximab
How does oestrogen affect growth of some tumours?
Can regular genes that promote growth
Which receptor family is HER-2 a member of?
The EGF receptor family
What can in situ hybridisation be used for?
Assessment of clonality in B cell lymphoid neoplasms via kappa and lambda light chain expression
Detection of EBV in EBV-encoded RNA
Identification of tumour-specific translocations
What type of receptor is HER-2?
A member of the EGFR family
It is a tyrosine kinase which promotes cell growth
What are the core members of an MDT who discuss the results of histology?
Surgeon
Radiologist
Oncologist
Histopathologist
What information is presented at MDT meetings?
Clinical, pathological and radiological information
