FOLLICULAR VARIANT OF PAPILLARY CARCINOMA OF THE THYROID - TO WHAT EXTENT IS FINE-NEEDLE ASPIRATION RELIABLE

We have reappraised the fine-needle aspirates (FNAs) of 5 cases of the follicular variant of papillary carcinoma of the thyroid (FVPCT). Thr ee of these had been performed an cold thyroid nodules and had been di agnosed as follicular proliferations. The remaining 2 had been perform ed on cervical lymphadenopathies and had been diagnosed as metastatic papillary carcinoma, probably of thyroid origin. Careful reassessment of the slides did nor allow any change of the the original diagnoses. We found two constant cytologic features present in all cases studied: syncytial clusters without acinar formation, and monolayered sheets. Nonconstant findings included: follicular pattern, ropy colloid, multi nucleated giant cells (MGCs), and nucleoli in FNAs performed on thyroi d nodules, and papillae, pseudonuclear inclusions, nuclear grooves, MG Cs, and nucleoli in FNAs performed on cervical lymphadenopathies. Our findings suggest that the cytologic diagnosis of FVPCT is very difficu lt if based solely on the cytologic features cs seen in FNAs, and that it is necessary to resort to the study of surgical specimens if a def initive diagnosis is to be achieved Ve are also of the opinion that mo re weight should be given to the aforementioned nonconstant findings w hen faced by a thyroid aspirate with cell richness, syncytial clusters without acinar formation, and monolayered sheets. (C) 1996 Wiley-Liss , Inc.