Carcinoembryonic antigen assay of intra-abdominal fine-needle aspirates

Differentiating abscesses from necrotic tumors has important therapeutic implications. Currently, cytologic examination is the "gold standard," but it has a low sensitivity for cystic/necrotic tumors. To address this problem, a prospective study was conducted comparing the results of cytologic examination with those of carcinoembryonic antigen (CEA) immunoassay of fine-needle aspirates in 24 patients undergoing radiologically or surgically guided fine-needle aspiration. Of 26 fine-needle aspirates, 20 were malignant and 6 benign. Final results were correlated with pathologic examination (when available), clinical review, and follow-up. Three patients had an abscess associated with perforated, recurrent carcinoma, of whom only one had cytologic assessment prior to drainage. The sensitivity of fine-needle aspiration was 85%, and for adenocarcinoma alone, 80%. CEA sensitivity (greater than 5 ng/mL) was 50%, and for adenocarcinoma, 90%; the specificity of the assay was 64%. A high CEA level alone was diagnostic of metastatic carcinoma of the colon in two fine-needle aspirates. Cytologic assessment and CEA assay of fine-needle aspirates and cyst/abscess drainage facilitate the diagnosis of unsuspected adenocarcinoma.