Preoperative fine needle aspiration of axillary lymph nodes in breast cancer: clinical utility, diagnostic accuracy and potential pitfalls.

OBJECTIVE: This study evaluates the diagnostic accuracy of axillary lymph node fine needle aspiration (FNA) cytology in breast cancer and correlates it with clinical parameters/outcomes. STUDY DESIGN: A total of 91 females underwent FNA of axillary lymph nodes at our institution from January 2007 to February 2013. The cases were classified as 'positive', 'negative for malignancy' and 'nondiagnostic'. RESULTS: Forty-six cases (50.5%) had a histologic follow-up (4.4 ± 3.1 months); of these, 22 (47.8%) were true positive, 7 (15.2%) were true negative, 2 (4.3%) were false negative, 5 (11%) were false positive and 10 (21.7%) were nondiagnostic. However, cytological review of all false positive and false negative cases confirmed the presence or absence of tumor, respectively. All false positive cases had undergone preoperative neoadjuvant chemotherapy, with no residual tumor present, and a treatment effect identified only histologically. Meanwhile, the 2 false negative cases involved micrometastasis (≤ 1.5 mm). Thus, if we exclude these false positive cases (complete responders), then the sensitivity, specificity, positive predictive value and negative predictive value were 91.7, 100, 100 and 77.8%, respectively. All preoperative FNA-positive axillary lymph nodes were spared from sentinel lymph node biopsy except for 3 of 27 (11.1%). CONCLUSION: We suggest that axillary lymph node FNA is a highly sensitive technique with a low false negative rate (4.3%) and a diagnostic accuracy of 93.5%.

Diagnostic use of muscle markers in the cytologic evaluation of serous fluids.

Differentiating reactive mesothelial cells from malignant mesotheliomas and from adenocarcinomas can be diagnostically challenging when based solely on the morphologic examination of serous fluids. The diagnosis even after the use of standard immunohistochemical stains may at times be inconclusive because of the variable reactivity of mesothelial cells for these markers. Pathologists and cytologists underutilize reactivity for desmin, a feature of mesothelial cells apparently not shared by adenocarcinomas. The purpose of this study was to evaluate the extent to which mesothelial cells express muscle differentiation and to assess the diagnostic utility of muscle markers in distinguishing reactive mesothelial cells from malignant mesotheliomas and adenocarcinomas. Archival paraffin-embedded cell blocks of serous fluids from 24 cases of reactive mesothelial cells, 14 cases of malignant mesothelioma, and 56 cases (14 cases from each) of metastatic adenocarcinoma from the lung, breast, ovary, and gastrointestinal tract were retrieved. Five cases of omentum with unremarkable mesothelial cells were also included in the study. All cases were stained for desmin, actin, myoglobin, and myogenin and evaluated independently by two observers. Strong cytoplasmic reactivity for desmin was noted in 22 of 24 cases (92%) of reactive mesothelial cells. The reactive mesothelial cells did not express actin, myoglobin, or myogenin. All cases of malignant mesothelioma and metastatic adenocarcinoma were negative for the four muscle markers. The mesothelial lining and scattered subserosal cells in the omental sections were positive for desmin. Because desmin was expressed only in benign mesothelial cells, it may serve as a reliable marker in distinguishing reactive mesothelial cells from mesothelioma or from adenocarcinoma. Awareness of this staining pattern is also important to avoid pitfalls when evaluating body fluid specimens from patients with a history of tumors expressing muscle differentiation.

Diagnostic utility of thyroid transcription factor-1 expression in adenocarcinomas presenting in serous fluids.

OBJECTIVE: To evaluate the diagnostic utility of the immunohistochemical expression of thyroid transcription factor-1 (TTF-1) in adenocarcinomas from serous fluid specimens. STUDY DESIGN: Archival paraffin-embedded cell blocks of serous fluids from 82 cases, including 34 cases of metastatic lung adenocarcinoma, 12 of metastatic ovarian adenocarcinoma, 12 of metastatic breast adenocarcinoma, 12 of metastatic gastrointestinal adenocarcinoma and 12 of malignant mesothelioma, were immunostained with anti-TTF-1. All the staining was carried out using a Ventana Automated System. Staining was evaluated according to the intensity of the nuclear staining (1+ to 4+) by two observers. RESULTS: Of the metastatic lung adenocarcinomas, 79% (27/34) expressed 3+ to 4+ reactivity against TTF-1. None of the malignant mesotheliomas or other metastatic adenocarcinomas expressed nuclear reactivity. CONCLUSION: Immunostaining with TTF-1 is a useful marker that can be applied to cytologic specimens. Anti-TTF-1 can be used as a reliable component of an antibody panel to support the diagnosis of adenocarcinoma of pulmonary origin in patients presenting with metastatic adenocarcinoma in serous fluid with an unknown primary site.

Endoscopic ultrasound-guided fine needle aspiration of the pancreas. Diagnostic utility and accuracy.

OBJECTIVE: Endoscopic ultrasound-guided fine needle aspiration biopsy (EUS-FNAB) is regarded as a safe and reliable procedure for diagnosing and staging of pancreatic neoplasms. This study retrospectively evaluated both the diagnostic utility and accuracy of pancreatic EUS-FNABs and potential cytologic pitfalls when using Diff-Quik stain for on-site evaluation. STUDY DESIGN: Pancreatic EUS-FNABs performed between 1995 and 1998 were identified from the files of the Department of Pathology. All patients were studied via a linear-array ultrasound endoscope with an FNAB device. Immediate evaluation of the specimen by a pathologist using air-dried slides and Diff-Quik stain was done on all cases. An average of five passes (range, three to nine) were performed. Five cytologic categories were identified: nondiagnostic, benign, atypical, suspicious and malignant. EUS disease staging, histologic correlation and clinical follow-up were reviewed. RESULTS: Sixty-nine consecutive pancreative FNABs were evaluated in the study period. The patients comprised 38 females and 31 males with a mean age of 65 years (range, 36-83). Histologic correlation was available on 40 patients, and follow-up was available on the remaining 29. The cytologic diagnoses included: 31 malignant, 8 suspicious, 6 atypical, 20 benign and 4 nondiagnostic. Forty-three cases were true positive, 9 were true negative, 2 were false positive, and 11 were false negative. The overall sensitivity was 80% and specificity was 82%. CONCLUSION: The study showed that cytologic evaluation of pancreatic EUS-FNABs has 80% sensitivity and 82% specificity. False negative diagnosis was usually due to sampling error. A nondiagnostic cytologic diagnosis should be rendered in the absence of adequate sampling of a lesion. On-site cytologic evaluation of EUS-FNABs aids in guaranteeing specimen adequacy, and the pathologist should be trained to evaluate Diff-Quik-stained samples.