Broadsheet number 57: problems in fine needle biopsy of the thyroid.

The role of fine needle biopsy and cytological diagnosis in the preoperative evaluation of thyroid nodules is reviewed on the basis of the current literature as well as the authors' personal experience. Technical aspects and guidelines for reporting thyroid samples are discussed in some detail. The main emphasis is on diagnostic pitfalls, those which may lead to a false-negative diagnosis, to a false-positive diagnosis or to an erroneous typing of the lesion, and their cytological patterns are described.