Background: Cytology is used to interpret cells obtained from various lesions. It is based on different sampling techniques that include fine needle aspiration cytology (FNAC), brush cytology, body fluids collection and study and collection of exfoliated cells. The use of cell block (CB) as an adjunct to routine fine needle aspiration can increase sensitivity to a considerable extent.
Objectives: to perform different techniques of cell block preparation and assess their utility in increasing the sensitivity of cytological diagnosis of fine needle aspiration cytology.
Patients and Methods: This was a prospective study carried out at Qena University Hospital's Department of Pathology (in the period from March 2021 to December 2022). The study included 40 individuals who were presented to the Outpatient Clinic of the General Surgery Department with thyroid nodules.
 Results: Concentrated formalin/ ethanol fixative (7 parts of 100 percent ethanol/ 3 parts of concentrated 40 % formaldehyde) method showed the highest diagnostic accuracy and the highest score. Out of 40 cases (FNAC of thyroid nodules), there were 28 cases given a score of 3, while 12 cases were scored 2, and none was scored 1.
Conclusion: The cell block approach enables the recovery and processing of minute amounts of cellular material, allowing for better tumor categorization and for immunohistochemistry stains. We found that concentrated formalin/ ethanol fixative (7 parts of 100 percent ethanol/ 3 parts of concentrated 40 % formaldehyde) based cell block showed the highest scores and the highest diagnostic accuracy in FNAC samples of thyroid nodules.