Adequacy of the specimen

Specimens may be unsatisfactory due to obscuring blood, overly thick smears, air-drying of alcohol-fixed smears or an inadequate number of follicular cells.
Specimens containing at least five groups of follicular cells, each composed of at least ten cells, are considered satisfactory for evaluation.

With experience, the average “unsatisfactory” rate is about 5% to 10%. It is incorrect to consider unsatisfactory or non diagnostic tests as negative. The lowest unsatisfactory rate will be achieved by close cooperation between the clinician and the cytopathologist, with immediate assessment of material. 

A follicle lined by bland thyrocytes. At least 5 such groups should be identified. In additon a macrophage with a typically vacuolated cytoplasm and a background of fluid colloid (bluish) can be seen.
A group comprising 3-4 normal follicles. The nuclei are round and the chromatin fine; cytoplasm is abundant, pale and indistinct. A peripheral "flare" is seen on the cell membrane, suggesting hyperfunctionality.
The result of an FNA with a 25G needleon a benign thyroid nodule. Note the very small central haemorrhage. There appears to be a correlation between entity of changes and size of needle, if prominent these changes may hamper histological correlation.
Inadequate smear (blood). A clearly inadequate smear at low power, showing blood only. Even if occasional thyroid cells may be present their identification is greatly hampered by excessive blood. Feed back between the sample taker and the cytologist are essential in order to decrease the number of such cases. The thyroid being a very vascular organ however, even in optimal circumstances a small proportion of cases will be inadequate.
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