DNA-based identification resolved suspected misdiagnosis due to contaminated cytological specimens

We report a clinical mishap based on sample contamination of cytological specimens. Bronchial lavage fluid collected from three male patients was submitted to a pathological institute for cytological diagnosis and to the clinical laboratory in the hospital for tuberculosis screening. Cytological slides of two patients were diagnosed as lung adenocarcinoma and lobectomy was carried out on one patient. However, diagnosis of the surgical specimen was tuberculoma. To resolve the discrepancy, genome DNA was isolated from patients' blood, cytological slide glasses and the mycobacterial culture tubes. Analysis of mitochondrial hyper-variable sequence and microsatellite revealed sample contamination in the cytological slide of the tuberculoma patient. DNA from the mycobacterial culture tubes showed identical results with the cytological slides, suggesting that the contamination occurred at the bed-side. Preservation of part of cytological specimen will be a help to avoid dispute between pathological laboratory and hospital over responsibility of incident.