[Rapid staining and guided fine needle aspiration for deep masses: a focus].

Ultrasound-, computerized tomography- or endoscopic ultrasonography-guided fine neddle aspiration (FNA) is a safe, rapid, and cost-effective method for securing a sample of abnormal tissue to diagnose and stage a variety of pathologic conditions in deep organs. The rate of false negative results is more dependent upon sampling failure and poor handling/preparation of aspirated material than on interpretation errors. This issue may be resolved in a cytopathologist is available at the time of the procedure to release a preliminary interpretation of air-dried, Diff-Quick-stained smears within a few minutes after performing the FNA. The immediate assessment can determine whether an adequate specimen is present, reduce the number of passes in each lesion, resulting in less discomfort and reduced likelihood of complications for the patient. A specific preliminary diagnosis may be rendered to guide further clinical investigation or treatment, and determine whether ancillary studies are needed to make a more accurate or specific diagnosis for the FNA specimen. Another advantage is the significant financial savings as compared to excisional tissue biopsy. But, rapid interpretation of the smears requires special training and is time-consuming. Accordingly, the indications have to be carefully determined, small-sized tumours are specifically recommended. A rapid evaluation increases the diagnostic yield, allowing near 100% in sensitivity, specificity and predictive value of positive cases.