[348] Fine Needle Aspiration of the Mediastinal Lesions: A 20-Year Retrospective Study of 561 Cases

Shaoxiong Chen, Harvey Cramer, Xiaoyan Wang. Indiana University, Indianapolis

Background: Image-guided fine needle aspiration (FNA) has been used routinely for diagnosing mediastinal lesions. In this study, we retrospectively reviewed our 20-year experience with FNA of the mediastinum and determined its diagnostic accuracy and clinical utility.
Design: A computerized search of our cytology database was performed for all FNAs of the mediastinum from 1990 to 2010. All cytology reports and correlating surgical reports were reviewed and slides from selected cases were re-examined.
Results: A total 561 FNA cases of the mediastinum were performed over a 20-year period. There were 329 malignant cases (59%), 157 benign cases (28%), 22 cases suspicious for neoplasm/atypical cells (4%), and 53 unsatisfactory cases (9%). Malignant cases included metastatic carcinoma (169 cases, 51%), thymoma/thymic carcinoma (45 cases, 14%), germ cell tumor (43 cases, 13%), lymphoma/leukemia (34 cases, 10%), primary neuroendocrine tumor (10 cases, 3%), and other rare poorly differentiated tumors (28 cases, 9%). Histological correlation was available for 238 FNA cases (42%) including 148 malignant, 57 benign, 11 suspicious for neoplasm/atypical cells, and 22 unsatisfactory cases. There were 32 patients diagnosed as metastatic small cell carcinoma by FNA who were directly referred for chemotherapy without ever obtaining a confirmatory surgical biopsy. Among 148 malignant cases, 141 (95%) cases were confirmed histologically; 4 malignant cases (3%) lacked histological confirmation due to biopsy sampling error and 3 cases (2%) were incorrectly classified by FNA including 1 case of lymphangiomyomatosis misdiagnosed as teratoma, 1 case of small cell carcinoma misdiagnosed as large cell lymphoma, and 1 case of sclerosing large cell lymphoma misdiagnosed as thymoma. Among 57 benign cases, 40 cases (70%) were confirmed histologically. However, there were 14 false negative FNA cases (25%) including 5 Hodgkin lymphomas, 3 adenocarcinomas, 2 large B cell lymphomas, 1 low grade neoplasm, 1 small cell carcinoma, 1 malignant peripheral nerve sheath tumor and 1 thymic carcinoma. Among 11 cases diagnosed as suspicious for neoplasm/atypical cells, 10 were proven to be neoplasms by follow-up histologically.
Conclusions: In this study, the overall diagnostic accuracy for the FNA diagnosis of mediastinal lesions was 88% and the misclassification rate was low (2%). False negative and unsatisfactory diagnoses were due primarily to sampling error. In our experience, FNA is a valuable method for the diagnosis of mediastinal lesions and is particularly beneficial for the management of patients with small cell carcinoma.
Category: Cytopathology

Wednesday, March 21, 2012 1:00 PM

Poster Session VI # 77, Wednesday Afternoon


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