The atypical cells in the pleural effusion smears stained with May Grunwald Giemsa - is it a new possible tool not to overlook malignancy?

Abstract

Malignancy is among the most frequent causes of pleural effusion. Its diagnosis is based on the detection of neoplastic cells either in the effusion itself or in pleural samples. Although mean sensitivity of pleural fluid(PF) cytology is 60%, the results may vary between centres.

To assess the diagnostic accuracy of PF smears stained with May Grunwald Giemsa (MGG, assessed by medical laboratory technologist) and with hematoxylin-eosin(HE, assessed by pathologist) in diagnosis of malignant pleural effusion(MPE).

We retrospectively analysed data of adults hospitalized due to PF in a 2-year period. Only simultaneously taken PF samples for MGG and HE stains were analysed. The samples were assessed positive if neoplastic cells (in HE stains) or atypical cells(in MGG stains) were detected. Diagnosis of MPE was made based on examination of pleural samples(thoracoscopy) or samples from abnormal tissue outside the pleura, but with sings of pleural involvement in CT scans. Then we calculated sensitivity, specificity, negative and positive predictive values (NPV and PPV, respectively) for both tests.

Paired samples from 283 patients were analysed(163 women, mean age 70 years). MPE was diagnosed in 143(50.5%) cases,(4/143 primary). PF samples stained with HE were positive in 44/283 cases and with MGG in 112/283 cases. Sensitivity, specificity, NPV and PPV for HE stained PF samples were 28%,96%,57%,89% and for MGG stains were 65%,87%,71%,84%, respectively.

To conclude:Traditional PF staining with HE showed very low sensitivity, whereas MGG stain seems promising in MPE diagnostics. Application of latter method may improve MPE diagnostics.