Tissue is obtained following puncture of the lesion and careful movement of the tip of the needle within the lesion; gentle suction may be applied.
For superficial palpable lesions the needle may be moved back and forth with a fanning action providing wider sampling and cell dislodgement.
In most cases, the aspirated material remains in the needle (unless cystis fluid present), and is then expressed onto pre-labelled slides and smeared out rapidly, or expressed into fixative for liquid based cytology.
Care needs to be followed when expressing material onto slides in patients with suspected infection eg, Tuberculosis. This should be undertaken in a biohazard cabinet.
Both air-dried and 70-95% ethanol or commercial wet fixed smears are preferred, but may depend on the tissue being sampled and on the preference of the reporting pathologist.
Tissue remaining within the needle, or a repeat aspirate, may be washed out in a non-fixative solution and used for microbiological examination, cytocentrifuge preparations, hormone receptor evaluation, cell block preparation, immunohistochemistry, cytogenetics, molecular genetics, or EM (special fixative).
If there is clinical suspicion of lymphoma or reactive lymph node, material may also be sent for cell surface markers.