Fine Needle Aspiration Cytology (FNAC)

FNAC means Fine Needle Aspiration cytology. It is a type of biopsy and one of the process of obtaining cytological specimen from a living body.

Aim

The main aim of FNAC is to rule out cancer. The sampling and biopsy is called FNAC or FNAB.

Other Wars

There are varieties of ways to get the specimens viz conventional cervical smear obtained by sampling the cervical transformation zone with a brush or broom, bronchial aspiration, washing and brushing gastrointestinal tract, biliary brushing samples etc for diagnosis of neoplasia.

Types

The process can be divided mainly into 2 types:

Superficial FNAC

In superficial FNAC cytological samples are obtained by FNAC from accessible sites e.g. breast, cystic (fluid  filled) lumps, thyroid, nodules or masses(solid lumps),superficial enlarged lymph nodes etc.

Deep FNAC

In this case cytological samples are collected from deeper and less accessible structures e.g. liver, pancreas, kidney, lungs etc. and usually  by ultrasonogram or C.T. guidence. USG guided transbronchial FNAC is done for mediastinal masses and transmucosal FNAC done for submucosal gastrointestimal lesions or perivascular lesions.

Sites

Sites for FNAC are a parts of body, lymph node, breast, liver, respiratory tract, oral cavity, thyroid, genital tract etc. but most common sites are breast ,Thyroid palpable lymph nodes

History of FNAC

To eliminate the need for surgery and hospitalization for histopathology, needle biopsy was first done in 1981 at Maimonides Medical Centre.

Uses

Usually, FNAC is done on swelling or lumps located just under skin. The lump may be felt during clinical exam in doctor’s chamber or abnormal spots deeper inside may be detected during x-ray or imaging e.g. C.T scan, Mammogram or Ultrasonogram. It is done when:

a. The natural of lump or mass is in question.

b.To asses the effect of Treatment in a known mass or tumour.

c. To obtain tissue for special study.

FNAC is the preferred method for Chorionic Villus Sampling and for various body fluid sampling. It is also used for ultrsonogram guided aspiration of breast abscess or breast cysts and seromas. Without biopsy it is hard for a doctor to confirm what these abnormal sites contain and if they are threat to patient.

Preparation

1. No use of Aspirin, blood thinner i.e. anticoagulant medications or NSAID (Brufen, Naproxen etc) .for one week before procedure.

2 .No food intake few hours before procedure

3.  Routine blood test including bleeding time and clotting time.

4. Antibiotic prophylaxis.

5 .Vital signs e.g. B.P., pulse, temp. are noted before procedure.

Articles Required

1 .5/10 c.c. syringe with 22-25 gauge needle.

2 . Antiseptic (Viodine-10%).

3. 2%Lignocaine.

4. Serile gauge.

5.Fixative

Procedure

Area of abnormally appearing tissue or having body fluid is cleaned, skin is swabbed with antiseptic and drapped with stinele surgical towels. Skin, underlying fat, muscle numbed with local anaesthesia. A small syringe with 25-22 G hollow needle is inserted to mass or lump and sample is collected by suction. A part of aspiration material is now submitted to laboratory for cytological assessment and other special studies.

Complications

Small amount of blood may appear in urine and after kidney biopsy. After lung biopsy blood may be seen in sputum or even pneumothorax may occur. However the small amount of lung collapse is automatically corrected. But in rare instance insertion of chest tube is required and patient is hospitalized.

Liver biopsy at times causes leakage of bile very and rarely spread of cancer cells along path of the needle. Pancreatitis may occur in case of pancreas .However death is very rare.

Conclusion

FNAC is minimally invasive very simple and effective procedure for diagnosis of malignant, inflammatory, infectious and degenerative condition. The sample can be also used for microbiological and biochemical analysis. It is a guiding tool before irreversible surgery, radiation and chemotherapy and can be easily performed even at out patient department in only about 30 minutes.

It is a valuable alternative to frozen section and results are available quickly. Of course one should be cautious about risk of transmission of HIV and Hepatitis B viruses. Negative result in breast lump is not so convincing but positive result means excision of breast or mastectomy. The target cell may be missed giving false negative result as  at times architecture of cells are not preserved. In those cases 2-3 samples collected from different areas of mass may give more accurate diagnosis.