Cell aggregates in malignant mesothelioma.

The finding in cell block sections of a central core of collagen within tumour aggregates in 4 out of 12 cases of effusions due to malignant mesothelioma is statistically significant (P greater than .01) when compared with its incidence in 2 of 80 cases of effusion due to metastatic carcinoma. It is suggested that this observation may be of diagnostic value in the cytologic evaluation of effusions when malignant mesothelioma is suspected.