Alginate encapsulated cell blocks improve diagnostic consistency and long term specimen integrity in routine pathological diagnostics and cancer research.

Cell blocks help preserve cytological material and facilitate ancillary diagnostics, but their accuracy is often compromised by uneven cell distribution and interference with immunohistochemical staining. We present an internally validated protocol for alginate-encapsulated cell blocks, which have been successfully used in routine pathology and during cancer research studies. Harvested cells were suspended in phosphate-buffered saline and centrifuged. Cell pellets were mixed with an alginate solution, immersed in 0.1 M calcium chloride to form conglomerates, fixed in 10% buffered formalin, processed in a tissue processor, embedded in paraffin, sectioned, and subjected to routine diagnostic protocols. Implementing alginate-encapsulated cell blocks in our laboratory allowed for the evaluation of pleural effusion, peritoneal effusion, and bronchial washings, with the cytopathological diagnoses matching the histopathological diagnoses in over 95% of cases analyzed. Cell blocks were internally validated against results obtained from histopathologic specimens and did not require manufacturer-provided kits. We have successfully applied the protocol to characterize the newly established mucoepidermoid carcinoma cell line (IHG-MUC360) expressing GOPC, with potent use in in vitro and in vivo studies. Integrating alginate encapsulation and cell block preparation significantly advances cytological diagnostics. Alginate-encapsulated cell blocks provide a cost-effective alternative to traditional methods, allowing long-term storage and re-evaluation of prepared samples. These findings are based on single-center internal experience and warrant further validation in larger, multicenter cohort.