Lab Diagnosis Of Neoplasia

Lab Diagnosis of Neoplasia By Sarah Iqbal Ahmed

 2. 3. 4. 5. 6. 7. 8.

These are the different methods used for diagnosis and staging of Neoplasia: Histological methods. Cytological methods Histochemistry and Cytochemistry Immunohistochemistry Tumour markers Flow Cytometry Newer methods

1.Histological Methods  Microscopic examination of properly fixed

tissue.  Tissue sample taken by:

Needle Aspiration

Cytologic Smears

Excision or Biopsy

 Selection of site is very important.  Samples are fixed in alcohol or

glutaraldehyde and then stained.

The samples are stained then examined under microscope.

2.Cytological Methods 

There are two methods:

1)Exfoliative Cytology/PAP smear: Study of cells shed off into body cavities.  Used for gyneac & non gyneac purposes.  Used for examination of : 1)Sputum 2)Bronchial washings 3)Pleural,Peritoneal & Pericardial effusions 4)Urine 5)Gastric secretions 6)CSF. 

FNAC(fine needle aspiration cytology)  Aspiration of cells and fluid under vacuum

 Followed by Cytologic examination of smear.  It is most commonly used method with a

reliability of 75-80%  It cannot be substituted for clinical judgment.

Frozen Section and Cryostatic Methods  Method of freezing and immediate

examination of samples. Eg:Surgeon sends margins of excised tumour to make sure if entire malignancy has been removed.

3.Histochemistry and Cytochemistry  Special staining methods to.

identify composition of cells, constituents and products.

4.Immunohistochemistry  Identifies specific components of cell by

specific monoclonal antibodies.  Antigen antibody complex is made visible by fluorescent dyes or enzyme systems. Melanoma stained by 3 antibodies (1)HMB-45 (2)CD-3.(3)CD-20

Uses of Immunohistochemistry  Categorisation of undifferentiated

tumours.Eg:Presence of keratin indicates epithelial cell tumour whereas desmin presence indicates neoplasia of muscle.  Determination of site of origin of metastasis spread.  Detection of molecules of prognostic importance.Eg: hormone receptors  Categorisation of Leukemia's and lymphomas

5.Tumour Markers  They are biochemical indicators of tumours

in blood or body fluids.  Products of tumour cells –also produced by normal cells.  They may be - cell surface antigens,enzymes, cytoplasmic proteins and hormones.  Measurement of these in serum is done by bioassays.  They help in identification of tumour and in measurement of prognosis.

TUMOUR MARKERS

TUMOURS

1. CEA

Colorectal and pancreatic neoplasm's Neoplasms of bone

3. Alkaline

phosphatase 4. Alpha fetoprotein Hepatocellular carcinoma,germ cell tumour of testis Choriocarcinoma 7. HCG Prostatic 8. PSA adenocarcinoma 9. CA-125 Ovarian tumours

6.Flow Cytometry  It is a Computerised technique by which Cytokeratin

detailed characters of individual cells are recognized and stored In-situ Hybridization:  DNA/RNA sequences are localized by specifically labeled probe in the intact cell  Used for detection of oncogenes and viruses

HPV

7.Other Methods DNA Microarray Analysis:  Conventional Molecular profiling of tumour by gene chip technology.  DNA probes substituted by silicon chip. Molecular Diagnostic techniques:  DNA/RNA extracted from cell and analyzed.  Eg:Southern blot,Northern blot and PCR(Polymerase Chain Reaction).

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