Lab Diagnosis of Neoplasia

By Sarah Iqbal Ahmed

These are the different methods used for diagnosis and staging of Neoplasia:

1. Histological methods.2. Cytological methods3. Histochemistry and Cytochemistry4. Immunohistochemistry5. Tumour markers6. Flow Cytometry7. Newer methods

1.Histological Methods

Microscopic examination of properly fixed tissue.

Tissue sample taken by:

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

and then stained.

Needle Aspiration Cytologic Smears Excision or Biopsy

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.

Special staining methods to. identify composition of cells, constituents and products.

3.Histochemistry and Cytochemistry

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

1. Categorisation of undifferentiated tumours.Eg:Presence of keratin indicates epithelial cell tumour whereas desmin presence indicates neoplasia of muscle.

2. Determination of site of origin of metastasis spread.

3. Detection of molecules of prognostic importance.Eg: hormone receptors

4. Categorisation of Leukemia's and lymphomas

5.Tumour MarkersThey 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

2. Alkaline phosphatase

3. Alpha fetoprotein

4. HCG

5. PSA

6. CA-125

Colorectal and pancreatic neoplasm's

Neoplasms of bone

Hepatocellular carcinoma,germ cell tumour of testis

Choriocarcinoma

Prostatic adenocarcinoma

Ovarian tumours

6.Flow Cytometry

It is a Computerised technique by which detailed characters of individual cells are

recognized and stored In-situ Hybridization:DNA/RNA sequences are localized by specifically labeled probe in the intact cellUsed for detection of oncogenes and viruses

HPV

Cytokeratin

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).

Thank you for listening!!!

Have a nice day.