Histological examination of clots from cytological specimens: is this a worthwhile procedure?

A comparison of conventional cytology and clot histology was made on 174 serous fluids, fine needle aspirates (FNA) and other non-gynaecological specimens. In eight cases (4.5%) this clot material contained malignant cells or cells suspicious of malignancy despite the absence of suspicious or malignant cells in conventionally prepared smears from the same specimen. In 11 cases (6.3%) the clot was negative, although conventional smears contained malignant or suspicious cells. A chi 2 test showed that there was no statistically significant difference between the number of positive diagnostic scores in each group with chi 2 of 0.223 (degree of freedom = 1), P = 0.637. Examination of clot material from serous fluids and FNA-aspirates is as effective as examination of conventional cytological preparations. Processing of clots from cytological aspirates for histological examination should be more widely adopted, and is applicable in all cytopathology laboratories.