Cell-block for diagnostic cytopathology: A touchstone in diagnosis

The cell block technique enhances sample adequacy in FNA specimens by enabling retrieval of small tissue fragments that can be processed into paraffin blocks for ancillary tests.

To determine the utility of the cell block technique by comparing cytomorphological and available immunohistochemical features.

This prospective study was conducted in the Department of Pathology over one year and included 56 cases in which FNAC, rapid onsite evaluation (ROSE), and cell block (CB) preparation were performed. FNAC smears were prepared using standard air-dried and alcohol-fixed techniques. ROSE was utilised to assess sample adequacy and guide additional passes for cell block preparation. Residual material and needle rinse samples were collected in fixative and processed using routine cell block techniques to obtain paraffin-embedded blocks. Both FNAC smears and CB sections were evaluated independently for cellularity, architectural patterns, cytomorphological features, and correlation with histopathology or immunohistochemistry wherever applicable. Sensitivity and diagnostic accuracy were calculated by comparing FNAC, CB, and combined FNAC+CB findings with final diagnosis.

A total of 56 cases were included: lymph node (39%, 22/56), intra-abdominal (30%, 17/56), soft tissue (16%, 9/56), head & neck (9%, 5/56), breast (4%, 2/56) and thyroid (2%, 1/56). Sensitivity for FNAC and CB was 96% and 98%, respectively, with a combined diagnostic accuracy of 97%.

Cell block is a simple and cost-effective adjunct that enhances diagnostic confidence when used alongside FNAC and should be considered whenever feasible.