Value of ancillary studies in the evaluation of fine-needle aspiration specimens: Our experience

Background: The cytological diagnosis of poorly differentiated tumors is challenging because the tumor cells may have morphologically difficult presentations in materials obtained by fine-needle aspiration cytology (FNAC). With the application of FNAC in primary diagnosis of malignant lesions, there has been a significant increase in the use of ancillary studies in the aspirated material. Aims: We evaluated the value of ancillary studies, namely cell blocks, immunocytochemistry (ICC) and electron microscopy (EM), in the final interpretation of FNAC smears. Materials and Methods: Sixty-nine cases of neoplastic swellings were subjected to FNAC. Material acquired was divided for ICC, consisting of immunoperoxidase staining of direct smears, and/or cellblocks and EM, in addition to routine light microscopy (LM). Correlation with the available histological material with immunohistochemistry and/or pertinent clinical information was used as a "gold" standard. Results: Five (7.2%) cases were excluded from the study, the material being necrotic or insufficient. Cell blocks were available in 46/64 (71.8%) cases, ICC evaluation was performed in 41/64 cases (64%) and EM studies were done in 57/64 cases (89%). Diagnostic accuracy of LM alone was 32/64 (50%). Cell blocks improved the diagnoses in 8/46 (17%) cases. The ICC data were diagnostic in 18/41 (43.9%) cases, helpful in 8/41 (19.6%) cases and non-helpful in 15/41 (36.5%) cases. EM studies were diagnostic in 22/57 (38.5%) cases, helpful in 18/57 (31.5%) cases and non-helpful in 17/57 (30%) cases. In 34/64 (53.1%) cases, all ancillary techniques (cell blocks, ICC and EM) were applied and their diagnostic accuracy was compared. Conclusions: With appropriate case selection, ancillary studies performed on aspirated material can provide useful information in FNAC.