RESUMEN
Objective: To determine optimal level of serial section in transbronchial and pleural biopsy that yield maximal definite diagnosis. Methods: A cross sectional study of 118 transbronchial biopsy and pleural biopsy specimens submitted with serial sectioning in 3 levels were performed. Specimens of 1 mm. in diameter were serially cut and slides at levels I, II, III (120, 240 and 360 µm.) from initial exposure of tissue in paraffin blocks were studied, and specimens of 2-3 mm. in diameter were cut at levels I, II, III (0, 120 and 240 µm.) after tissues in paraffin blocks were trimmed to expose maximal diameter. Comparisons of diagnoses of each level were done. Results: The percentages of definite diagnoses were 89, 95.8 and 93.2 in sections of level I, II and III, respectively. Chronic granulomatous lesions were found in section level II more than other levels, but there was no statistical significance. (P value 0.131, Chi-Square test) Conclusion: Transbronchial and pleural biopsy specimens should be cut deep to level II, one slide for hematoxylin-eosin staining and 3 unstained slides for further investigation.