Utility of electron microscopy in the assessment of transthoracic needle lung biopsy specimens.

RATIONALE AND OBJECTIVES: The authors determine the usefulness of electron microscopy (EM) in the workup of patients with certain intrathoracic masses undergoing transthoracic needle biopsy (TNB). METHODS: Over a 4-year period, 1603 patients underwent TNB at our institution. Of these, 79 had EM examination of the aspirated material. The study is a retrospective review of this latter group. Previous use of EM for TNB had suggested that it may he helpful in those with pleural, chest wall, and mediastinal lesions. The 40 men and 39 women had pulmonary (n = 49), mediastinal (n = 17), pleural (n = 10), and chest wall (n = 3) lesions. RESULTS: The adequate specimen rate was 59% (47 of 79) for light microscopy (LM) and 37% (29 of 79) for EM. Of the 28 patients with satisfactory specimens for both LM and EM, the correct diagnosis was obtained by LM 79% (22 of 28) and EM 96% (27 of 28) of the time. Electron microscopy was most helpful in patients with mediastinal (6 of 6 correct versus 3 of 6 for LM) and pleural (3 of 3 versus 1 of 3) lesions. CONCLUSIONS: In specific circumstances, EM can be a very useful adjunct to LM in patients undergoing TNB. Problems with sample adequacy must be addressed.