Cystic thyroid nodules. The dilemma of malignant lesions.
A retrospective study of 221 surgically resected thyroid nodules disclosed that 71 (32%) were cystic and 150 (68%) were solid lesions. Ultrasonography correctly characterized cystic nodules in all but one case. Comparing cystic and solid nodules, there were no differences in patient demographics (mean ages, 47.7 +/- 1.8 SEM vs 45.9 +/- 1.2 years; sex, 78% females both groups), the proportion that were solitary (39% vs 40%), or the nodule size (49% vs 47% greater than or equal to 2 cm in diameter). Of cystic thyroid lesions, 4% were simple cysts, 82% were degenerating benign adenomas or colloid nodules, and 14% were malignant compared with 23% of solid lesions that were malignant. Most cystic lesions (81%) contained bloody fluid. One benign true cyst was filled with thick brown fluid, while clear yellow fluid was repeatedly aspirated from one malignant cystic nodule. Malignant fine-needle aspiration cytology was the best predictor of cancer (100%). Much less predictable were signs of local compression or invasion (43%), a history of head or neck irradiation (33%), cyst recurrence after aspiration (29%), or an increase in the cystic nodule's size (7%). Indeterminate cytology identified malignancy with about half the frequency in cystic lesions as compared with solid nodules (13% vs 27%). The only false-negative fine-needle aspiration cytology occurred in a cystic lesion. In patients with cystic papillary cancers, needle aspirates contained insufficient material for diagnosis in 20% that occurred in no patient with solid papillary carcinoma. The sensitivities and specificities of fine-needle aspiration cytology for solid nodules were 100% and 55%, and for cystic nodules were 88% and 52%. Thus, cystic lesions are as likely as solid thyroid lesions to harbor a malignancy that cannot be predicted from the cyst's clinical characteristics or the patient's demographic data. Although fine-needle biopsy is the best predictor of malignancy in either cystic or solid thyroid lesions, it is slightly less reliable when a thyroid lesion is fluid filled rather than solid. We believe that most cysts not abolished by aspiration should be surgically excised.
Department of Endocrinology, Ohio State University, Columbus.
E T
ET
de los Santos
S
S
Keyhani-Rofagha
J J
JJ
Cunningham
E L
EL
Mazzaferri
D000328:Adult; D001707:Biopsy, Needle; D002291:Carcinoma, Papillary / Q000175:diagnosis / Q000601:surgery; D003560:Cysts / Q000175:diagnosis* / Q000601:surgery; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012008:Recurrence; D012189:Retrospective Studies; D013959:Thyroid Diseases / Q000175:diagnosis* / Q000601:surgery; D013964:Thyroid Neoplasms / Q000175:diagnosis* / Q000601:surgery; D014463:Ultrasonography