Paul J. Michaels

BACKGROUND: Intraductal papillary mucinous neoplasm (IPMN) is an increasingly recognized cystic neoplasm of the pancreas, histologically classified by the degree of epithelial atypia and by the presence or absence of invasion of the cyst wall. To the authors' knowledge, the cytologic features of this neoplasm are poorly characterized, especially with respect to tumor grade. METHODS: Thirty-three endoscopic ultrasound (EUS)-guided pancreatic fine-needle aspiration biopsy (FNAB) samples and 1 pancreatic duct brush specimen from 25 patients with a histologically confirmed IPMN were retrospectively reviewed. Blinded to tumor grade, background mucin, inflammation, necrosis, overall cellularity, the presence of gastrointestinal-contaminating epithelium, architecture of cell clusters, and nuclear and cellular morphology were evaluated. In cases in which special stains for mucin were performed, the diagnostic utility of these stains was assessed. These cytologic features were subsequently correlated with the histologic diagnosis. RESULTS: The 34 cytology samples represented 4 adenomas, 15 IPMN-moderate dysplasias, 7 intraductal carcinomas, and 8 IPMNs with invasive carcinoma. Extracellular mucin was present in 97% of all cases; 53% had thick, viscous, "colloid-like" mucin. Special stains for mucin were positive in 6 of 11 cases (54%), helping to identify thin mucin in only 2 cases. Gastrointestinal contamination did not appear to create diagnostic difficulty due to an apparent dual (dysplastic-nondysplastic) epithelial population, but only 4 adenomas were evaluated in this study. Necrosis distinguished IPMN with carcinoma from IPMN-adenomas and IPMN with moderate dysplasia (P < .00001), and was more often observed with invasion than IPMN-carcinoma in situ (P < .05). Tight epithelial cell clusters with hyperchromatic nuclei and a high nuclear to cytoplasmic ratio was more significant in IPMN of at least moderate dysplasia (P = .03). Pale nuclei with parachromatin clearing was found to be a nuclear feature that was suspicious for at least carcinoma in situ (P < .001). In addition, significant background inflammation (neutrophils and histiocytes) was found to be more characteristic of IPMN with at least carcinoma in situ (P = .002). CONCLUSIONS: The presence of thick, "colloid-like" mucin is noted in half of the IPMN cases, but was not found to be specific to grade. The absence of such mucin does not exclude an IPMN. The presence of tight epithelial cell clusters is consistent with a neoplasm of at least moderate dysplasia, and abundant background inflammation and parachromatin clearing correlated with the presence of at least carcinoma in situ. Necrosis was the only feature found to be strongly suggestive of invasion.

BACKGROUND: Secondary neoplasms of the thyroid gland (SNTGs) are uncommon, and it is important to recognize them in thyroid fine-needle aspiration biopsy (FNAB). METHODS: The authors report a cohort of 62 SNTGs from 7 institutions in the United States and Europe. Patients were identified retrospectively by searching through medical records of the respective institutions. All initial diagnoses were rendered by FNAB. RESULTS: SNTGs represented 0.16% of all thyroid FNABs and were more frequent among women (ratio of women to men, 1.2:1.0). The mean patient age was of 59 years (range, 7-84 years), the mean tumor size was 3 cm (range, 0.9-7 cm), and the mean interval from diagnosis of the primary tumor was 45 months (range, 0-156 months). Eighty-seven percent of SNTGs were diagnosed as malignant by FNAB, and there was a specific SNTG diagnosis in 93% of patients. Immunocytochemistry and flow cytometry, which were used in 30% of patients, were useful ancillary studies. Adenocarcinomas (n = 23; 37%) and squamous cell carcinomas (SCCs) (n = 22; 35.5%) represented the majority of SNTGs, followed by lymphoma (n = 5; 8%), melanoma (n = 5; 8%), adenoid cystic carcinoma (n = 3; 5%), and various sarcomas (n = 3; 5%). Adenocarcinomas originated from the kidney (n = 9; 39%), lung (n = 6; 26%), breast (n = 5; 22%), and colon (n = 3; 13%). SCCs originated mostly from the head and neck (n = 13; 59%), followed by lung (n = 3; 13%), esophagus (n = 3; 14%), and unknown primary sites (n = 3; 14%). CONCLUSIONS: Adenocarcinomas from the kidney, lung, breast, and colon along with SCCs represent the majority of SNTGs. The current results indicate that FNAB is a sensitive and accurate method for diagnosing SNTG; however, diagnostic difficulties can occur. Knowledge of clinical history and the judicious application of ancillary studies can increase the sensitivity and accuracy of FNAB for detecting SNTGs.