Cytology

Cytology

1. Exfoliative cytology

2. Interventional /aspiration cytology

EXFOLIATIVE CYTOLOGY: It is the study of cells shed off from the epithelial surface spontaneously, into body cavities or into body fluids. I also include study of the cells obtained by scrapping, brushing or washing of body surfaces. The principle of this technique is that in disease states, rate of exfoliation of cells is increased.

Collection of materials – Materials are collected from different sites of the body with minimal contamination. With the material obtained smears are prepared and fixed immediately. The different sites from where materials are collected include:

1. Female genital tract

a) Cervical smear – Ectocervix and endocervix

b) Vaginal smear - Lateral vaginal wall

c) Vaginal pool smear

2. Respiratory tract

a) Sputum

b) Bronchial brushings

c) Bronchial washings

d) BAL (Broncho Alveolar Lavage)

3. GIT

a) Scrapping with metallic/wooden spatula of oral cavity

b) Brushing/lavage during endoscopy

4. Urinary tract

a) Urinary sediments from voided urine /catheterized urine

b) Washings of urinary bladder from cystoscopy

5. Body fluids:Pleural, pericardial or peritoneal cavities

6. Oral cavity:Buccal smear for checking Barr bodies

7. Others: CSF, synovial fluid, nipple discharge, seminal fluid, amniotic fluid etc..

APPLICATIONS:

a) Early detection of cancers

b) Endocrine evaluation for hormonal therapy

c) Estimation of cell response to radiotherapy and follow up of post-operative therapy.

d) Study of cytogenetics

e) Immunocytology

INTERVENTIONAL CYTOLOGY: Samples are obtained from the lesion by fine needle aspiration.

Indications of FNAC

I. Palpable lesions:

1. Lymph nodes

2. Breasts

3. Thyroid

4. Salivary gland

5. Soft tissue masses

6. Bones

II. Non-palpable lesions - approached with radiological guidance

1. Abdominal cavity

2. Thoracic cavity

3. Retroperitonium

Advantages

1. Can be done as a preoperative procedure

2. No hospitalization needed. .

3. No anesthesia required.

4. It is quick, safe and relatively painless

5. Can be repeated i.e. multiple attempts are possible

6. Low cost

7. Quick results can be obtained

Disadvantages

1. Require skilled personals

2. False diagnosis when target lesion is missed.

Materials needed.

1. 22-23 Gauge needle(disposable)

2. Disposable 10 ml syringe

3. Glass slide

4. Coplin jar with fixative

Types of slide preparation:

1. Air dried smears

2. Fixed smears

Fixation and fixatives used in cytology

Rapid fixation of smears is necessary to preserve cytologic details of cells spread on a slide.

Smears should remain in the fixative for a minimum of 15min prior to staining. Air dried smears are used for staining with MGG stain.

Fixative used

100% Methanol

95% Ethanol( ideal fixative)

95%Denatured alcohol

80% Propanol

80% Isopropanol

Staining

1. Papanicolaou stain: best for routine cytological examination. This is the stain used in cervical smears. Hematoxylin is the nuclear stain, while OG (Orange G) and EA (Eosin Azure) are the two cytoplasmic stains.

2. H&E stain.

3. Romanowsky stain.

Nuclear details are best seen in pap stain while cytoplasmic details are seen better in Romanowsky stain.

Special stains like PAS, methyl violet and Congo red are also used. Immunohistochemical stains can also be done on cytological smears and on cell block preparations.