Fine needle aspiration cytology

After clinical examination and imaging procedures have been carried out and a 'lump' has been documented, a definitive diagnosis is required. The latter can be established by carrying out fine needle aspiration cytology (FNAC) obviating the need for a formal biopsy (requiring surgery) or a core or TruCut biopsy (which can be uncomfortable for the patient).

FNAC is performed using a standard (10 ml) syringe and needle (21G); a special gun containing the syringe may be used. The needle is inserted into the palpable lump and suction is applied to the syringe in order to aspirate material into the needle. Multiple passes are made into the lump, in a range of directions, in order to obtain as representative an aspirate as possible. The needle is then withdrawn from the lump and the contents of the needle spread out onto

Figure 17.10. Mammographic appearances of a breast cancer showing increased density and architectural changes.

Figure 17.11. (a) Mammographic appearances of a breast cyst.

Figure 17.10. Mammographic appearances of a breast cancer showing increased density and architectural changes.

microscope slides, with some being dried in air and others put into a fixative solution. The cells can then be stained (e.g. Giemsa, Papanicolaou, haematoxylin and oesin) prior to microscopic examination. Many major centres have a cytol-ogist present at the breast clinic who will examine and report on the breast aspirates whilst the patient is at the clinic and an immediate report is provided. The scoring system used for reporting the results of FNAC is shown in Table 17.1. The sensitivity of FNAC is approximately 95% (ranging from 80% to 99%), with a specificity of 98% (ranging from 95% to 99%) (Figs 17.12 and 17.13).

Figure 17.11. (a) Mammographic appearances of a breast cyst.

If a lesion in the breast has been detected on either mammography or ultrasonography (but is not clinically detectable) then cytological examination of the lesion can still be made. This is carried out either stereotactically using mammographic-guided fine needle aspiration (FNA) or by ultrasound-guided FNA. Established centres using triple assessment (clinical examination, imaging (mammography, ultrasonography) and FNAC) report a sensitivity of more than 95%, specificity of more than 96% and a predictive value of more than 97%, with this approach. However, in some patients it is still not possible to make a definitive diagnosis despite use of triple assessment and in these cases a biopsy will be required for histological examination.

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