PSAMMOMA BODIES IN FINE-NEEDLE ASPIRATES OF THE THYROID - PREDICTIVE VALUE FOR PAPILLARY CARCINOMA

BACKGROUND. Although characteristic of thyroid papillary carcinoma, ps ammoma bodies occasionally arise in benign or nonpapillary lesions. Th eir predictive value in fine-needle aspirates (FNA), without other fea tures suggestive of papillary carcinoma, is uncertain. METHODS. This r etrospective study determined the frequency of psammoma bodies and oth er calcifications in 313 FNAs and 69 resected thyroids; positive predi ctive value, sensitivity, and specificity were calculated and compared with a triad of characteristic cytologic features (papillary fronds, nuclear ridges/grooves, and intranuclear inclusions). Psammoma bodies from benign and malignant conditions were assessed for differentiating architectural or staining characteristics. RESULTS. Psammoma bodies w ere found in only 8 of 313 FNAs. Their positive predictive value for p apillary carcinoma was 50%, the rest arising from multinodular goiters . By contrast, the positive predictive value of combined cytologic fea tures was 100%. These features were also much more sensitive, present in 80% of papillary carcinomas compared with 14% with psammoma bodies. The psammoma bodies of papillary carcinoma could not be differentiate d from those of other lesions either by staining characteristics or by architecture. Other types of calcifications also were present in dive rse conditions, and did not discriminate among them. CONCLUSIONS. Isol ated psammoma bodies are an unreliable predictor of papillary carcinom a in the absence of cytologic features. In view of the relatively low aggressiveness of papillary carcinoma in most age groups, repeat fine- needle aspiration and clinical con elation are recommended prior to co nsideration of surgery. (C) 1998 American Cancer Society.