College of American Pathologists
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cap today

May 2003
Special Section

Can mucinous lesions be diagnosed reliably by core needle biopsy?

Emily Volk, MD

Much difficulty is associated with the diagnosis of mucinous breast lesions by fine-needle aspiration biopsy. Numerous published studies have determined that FNA is not a reliable technique for evaluating mucinous breast lesions because they can be associated with a false-negative specimen. For example, an FNA of a colloid carcinoma may yield abundant mucin and few malignant cells, possibly leading to a false-negative diagnosis. Until recently, however, the reliability of core needle biopsies in the evaluation of these lesions had not been examined. Andrew Renshaw, MD, contributes a significant paper to the paucity of literature on core biopsy evaluation of mucinous breast biopsies (Am J Clin Pathol. 2002;118:82-84).

He evaluated more than 4,000 breast core needle biopsies over about five years. He found 22 cases of mucinous lesions; 15 of these had accompanying excisional biopsy material. He found that these lesions can be accurately classified on core biopsy, in contrast to the known difficulty associated with FNA of these same lesions. Although the actual number of mucinous lesions evaluated is not large, this is the largest series of its kind in the literature and therefore definitely worth reviewing.

Dr. Volk, a member of the CAP Cytopathology Committee, is in the Department of Pathology, William Beaumont Hospital, Troy, Mich.