Ultrastructure of pleural mesothelioma and pulmonary adenocarcinoma in malignant effusions as compared with reactive mesothelial cells.
OBJECTIVE
To determine the ultrastructural features of diffuse malignant pleural mesothelioma cells in cytologic specimens from pleural effusions.


METHODS
We retrospectively studied 35 pleural effusions: 12 diffuse malignant pleural mesotheliomas (8 epithelial type, 4 biphasic type), 12 pulmonary adenocarcinomas and 11 cases of reactive mesothelial cells.


RESULTS
In the cytoplasm, reactive and malignant mesothelial cells had more-abundant intermediate filaments (P < .05, P < .01) and fewer free ribosomes (P < .001, P < .001) than adenocarcinoma cells. Reactive mesothelial cells had fewer mitochondria than mesothelioma cells (P < .05). Mesothelioma cells had longer, thinner microvilli on the cell surfaces (P < .001); length/diameter ratios of microvilli were 19.1 +/- 7.0 (mesothelioma) vs. 9.1 +/- 2.2 (adenocarcinoma) and 9.2 +/- 2.4 (mesothelial cells). Giant intercellular junctions (desmosomes or desmosomelike structures > 1 micron in length) were found in eight cases of mesothelioma. Core filaments or rootlets in microvilli were present in two cases of adenocarcinoma.


CONCLUSIONS
Because cytologic specimens from pleural effusions were easy to obtain, we think ultrastructural cytology is useful in distinguishing mesothelioma from adenocarcinoma and benign effusions.
Sakuma
N
N
First Department of Pathology, Yamaguchi University School of Medicine, Ube, Japan.
Kamei
T
T
Ishihara
T
T
D000230:Adenocarcinoma / Q000648:ultrastructure*; D004396:Coloring Agents; D003896:Desmosomes / Q000473:pathology / Q000648:ultrastructure; D004848:Epithelium / Q000473:pathology / Q000648:ultrastructure; D006801:Humans; D007365:Intercellular Junctions / Q000473:pathology / Q000648:ultrastructure; D008175:Lung Neoplasms / Q000648:ultrastructure*; D008654:Mesothelioma / Q000648:ultrastructure*; D008871:Microvilli / Q000473:pathology / Q000648:ultrastructure; D008928:Mitochondria / Q000473:pathology / Q000648:ultrastructure; D016066:Pleural Effusion, Malignant / Q000473:pathology*; D010997:Pleural Neoplasms / Q000648:ultrastructure*; D012270:Ribosomes / Q000473:pathology / Q000648:ultrastructure
D004396:Coloring Agents