Fine needle aspiration cytology (FNAC) or Fine needle aspiration biopsy (FNAB) is a diagnostic procedure which is used to investigate superficial lumps or masses just under the skin. In this method, a hollow and thin needle is inserted into the mass for the purpose of sampling of cells. After being stained, they will be examined under a microscope. There is a cytology examination of aspirate or histological biopsy; this is equivalent of cell specimen evaluation.
Fine needle aspiration cytology is safe and a minor surgical procedure. In very rare cases, a major surgical excision or open surgery or biopsy can be avoided by performing a needle aspiration biopsy. The first fine needle biopsy was carried out in USA in 1981 at the Maimonides Medical Centre, eliminating the need for hospitalization and surgery.
Today, this procedure is used widely in diagnosis of inflammatory conditions and cancer. It is a less traumatic procedure than an open surgical biopsy. Common complications arising out of this procedure are only soreness and bruising. As the biopsy level is small where only a few cells are taken as sample, there is a risk that the actual problematic cells may be missed out and the diagnosis may not be an effective one.
A fine needle aspiration sampling is done when a biopsy is performed on a lump or a tissue mass when there is a question about its nature and it is also done for known tumours where the biopsy is done to assess the effect of treatment or to gather tissues for some special studies. When a lump can be felt, the biopsy is usually done by a cytopathologist or a surgeon. The procedure is a short and a simple one. In rare cases, it is done by an interventional radiologist or a doctor who is trained in performing such biopsies under X-ray or Ultrasound guidance. In such cases, the procedure will require extensive preparation and it will take up more time to perform.
Fine needle aspiration is the major method that is used for various types of body fluid sampling and for chorionic villus sampling. It is also used for ultrasound-guided aspiration of breast abscess, breast cysts and of sarcomas.