0507 - Investigating Disseminated Malignancy Flashcards
What is a neoplasm?
An abnormal mass of tissue, the growth of which:
exceeds and is uncoordinated with that of the normal surrounding tissue; and
persists in the same excessive manner after the cessation of the stimuli which evoked the tumour (e.g. still grows even if you quit smoking).
What is Metastatic Disease
Situation where tumour implants away from the primary tumour. It is the hallmark of malignant tumours.
By what mechanism can metastases spread?
Can spread by lymph, blood vessels, perineurally, or seeding of body cavities (e.g. via peritoneum).
What is meant by the concept of unknown primary tumour?
First presentation is itself a metastatic disease (e.g. lymphadenopathy, femoral neck fracture), and primary site is not appreciated on routine examination.
80% of time, brain tumours are mets rather than a glial tumour.
Why is it important to understand the type of tumour primary?
Target Treatment
More accurate Prognosis
Genetic Counselling
Accurate cancer statistics
What is the pathologist’s role in investigating unknown primary tumour?
Interpret serum tumour markers, biopsy, and IHC. Tumour difficult to find on examination and even investigation sometimes. Rely on pathologist to identify cell type and find type of tumour primary (particularly via IHC), and even source organ by looking at architecture.
Briefly outline serum tumour markers (conceptually).
Molecules that are overexpressed in, and shed into the blood by tumour cells. Usually glycoproteins and detected by monoclonal antibodies.
Most useful in assessing response to therapy and determining recurrence.
What are some examples of tumour markers?
CEA - carcinoembryonic antigen - Adenoma
AFP - alpha fetoprotein - HCC and germ cell tumours
CA125 (Cancer Angigen 125) - Epithelial ovarian cancer
PSA - Prostate Specific Antigen - Prostatic adenocarcinoma
CA19.9 - Pancreatic cancer
Briefly outline Biopsy in investigations of tumour of unknown primary
Can be FNA, core, or excision. FNA goes for cytology, others go for histology.
Look at architecture and cellular characteristics.
By assessing morphology, you can determine type and thus know the preferred route of metastasis. Thus can help you find the primary by following it back.
How is IHC used in investigating a tumour of unknown primary (KEY EXAM CONCEPT)
Antibodies synthesised to hit a particular target. Morphology gives an index of suspicion as to what’s most likely. Then targeted by a coloured, tagged antibody which will show on light microscopy. By targeting a particular aspect of a cell (e.g. a CD), it can idenfity the lineage of cell and/or the organ of origin.
What are some common IHC targets for determining cell type? (Epithelial, Mesenchymal, Lymphoid, Melanocyte)
Carcinoma - Cytokeratin Sarcoma - Vimentin Lymphoma - Leucocyte Common Antigen Melanoma - S100 There are multiple sub-types for each, and cells from different locations have different profiles for these IHC targets.
