Staining for acid-fast bacilli in surgical pathology: practice patterns and variations

Summary Analysis of acid-fast bacilli stains on sputum smears for the diagnosis of tuberculosis has a long history, but quality control for acid-fast bacilli in histologic sections is not as well established. In tissues, necrotizing granulomas are closely linked to positive cultures for mycobacteria. However, the practices of pathologists examining acid-fast bacilli in surgical specimens are not well described in the literature. This study characterizes practice patterns related to the histologic interpretation of acid-fast bacilli stains. A survey invitation was sent to 1299 pathologists including members of the Pulmonary Pathology Society and randomly selected fellows of the College of American Pathologists. Twenty-one questions inquired about demographics, ordering and interpreting acid-fast bacilli stains, reporting, and correlation. Of the 392 responses (30.2% response rate), 363 respondents review acid-fast bacilli stains on histologic sections. Approximately half of respondents practice in an academic setting, with the other half in community practice. Most respondents examine the entire acid-fast bacilli slide with the ×40 objective; approximately half confirm the organisms under oil immersion at ×100. There was considerable variation in when an acid-fast bacilli stain is ordered, as well as possible additional workup for negative cases, reporting of results, correlation with clinical and culture findings, and training. Many respondents reported never having been taught a general approach to acid-fast bacilli interpretation. There is substantial variation in practice patterns involving all aspects of ordering, histologic examination, and reporting of acid-fast bacilli stains. Future efforts to standardize the interpretation of acid-fast bacilli stains can potentially improve the diagnosis of mycobacterial disease.