Diagnostic utility of cell blocks and an immunomarker panel in the cytological evaluation of serous effusions

Introduction: Cell blocking (CB) has gained wide acceptance as an integral diagnostic tool in cyto-diagnosis. It allows retrieval and concentration of exfoliated cells in fluid specimens to form paraffin blocks that are interpreted in a biopsy like fashion. The aim of this study was to compare the diagnostic utility of CB to conventional smears (CSs) in the evaluation of serous effusions and to evaluate whether the tested immunomarker panel increases the diagnostic yield of malignancy. Materials and Methods: Serous effusion specimens were processed using both techniques; CSs and CB. An immunomarker panel (Ber-EP4, EMA E29, D2-40 and desmin) was then applied on CB sections. Results: CB enhanced the cellularity; it increased the diagnostic yield by 27.4% over CSs. Both nuclear and cytoplasmic details were better demonstrated in CBs. CBs were superior in the preservation of architectural patterns as acini, papillae and sheets. The diagnosis of CBs concurred with that of CSs in 79% of cases, however the diagnostic yield of malignancy increased by 9.6% using CBs. Adding the immunomarker panel totally eliminated the suspicious category and further increased the diagnostic yield for malignancy by 9.7% over CBs and by 19.3% over CSs. Furthermore, categorization of malignant cases into primary malignant mesothelioma and metastatic carcinoma was feasible after thorough interpretation of the combined immunoprofile. Conclusion: CB represents a cost-effective adjunct to CSs in the evaluation of serous effusions. It increases the cellular yield, provides superior cytomorphology, architectural preservation, and supplies material for ancillary studies.