Radiologically-determined diameter, pathologic diameter, and reactive zone surrounding pulmonary neoplasms: implications for transthoracic fine-needle aspiration of pulmonary neoplasms.

To determine the relationship between radiologically determined tumor diameter and true pathologic tumor diameter and correlate radiologically determined diameter with the size of reactive zone surrounding pulmonary neoplasms, radiographs and surgical pathology specimens were obtained from 57 patients with pulmonary neoplasms. The tumor size on plane films and CT-scans was measured, as was the size of the neoplasm on gross specimen and surgical pathology slide. The width of the reactive zone was also measured on H&E stained microscopic slides. These findings were correlated along the histopathologic type of neoplasm present. On average, the reactive zone represented approximately 11% of the overall diameter of the neoplasm. However, there was considerable variation in this percentage, with reactive zone thickness varying between 2% and 48% of total tumor diameter. Bronchioloalveolar cell carcinomas generally lacked a reactive zone, while the other types of carcinomas frequently contained reactive zone. Approximately half of all carcinomas displayed a reactive zone of 1 mm in thickness or more. The present study demonstrates that a majority of carcinomas contain a reactive zone. This reactive zone is of variable thickness, but in approximately 50% of carcinomas it is at least 1 mm in thickness. The thickness of the reactive zone represents approximately 11% of total tumor diameter. Diagn. Cytopathol. 1999;21:250-252. Copyright 1999 Wiley-Liss, Inc.