Morules and morule-like features associated with carcinomas in various organs: report with immunohistochemical and molecular studies.
BACKGROUND
Morules have been reported in pulmonary blastoma (PB), well differentiated fetal adenocarcinoma of the lung (WDFA), and uterine endometrioid carcinoma (EC), and rarely in other carcinomas. beta Catenin gene mutation has been associated with morule formation.


OBJECTIVE
To compare and clarify the cellular characteristics of morules in carcinomas in various organs and show that morules are distinct from epithelial cellular nodules.


METHODS
Twenty tumours were studied: two PBs, three WDFAs, three papillary lung adenocarcinomas, 11 ECs, and one papillary thyroid carcinoma. Numerous epithelial cell, oncofetal, and neuropeptide antibodies were used for immunohistochemistry. beta Catenin gene mutation was investigated.


RESULTS
Morules in PBs and ECs were uniform cell clusters distinct from squamous differentiation. All were immunonegative for epithelial cell and oncofetal antigens, but those in ECs were positive for neurone specific enolase gamma (NSEgamma). Synaptophysin, encephalin, and somatostatin were sporadically immunopositive in PB morules. Morules were not seen in the other carcinomas and WDFAs, although morule-like features closely resembling morules histopathologically were seen. These were positive for epithelial cell and oncofetal antigens, and showed squamous differentiation. Their nuclei were more atypical and slightly larger than those in morules. Morule-like features were seen in WDFAs. beta Catenin gene mutation was demonstrated in one EC and PB, and in two WDFAs.


CONCLUSIONS
Morules were non-epithelial cell clusters showing neuronal differentiation. There were two types: endometrioid type, expressing NSEgamma, and blastoma type, expressing neuropeptides. In contrast, similar morule-like features were epithelial nodules. Although the number of cases was small, the presence of morules showed no clear prognostic correlations.
Makishi
S
S
Division of Pathology and Cell Biology, Graduate School and Faculty of Medicine, University of the Ryukyus, 207 Uehara, Nishihara, Okinawa 903-0215, Japan. k048718@eve.u-ryukyu.ac.jp
Kinjo
T
T
Sawada
S
S
Chinen
K
K
Hirayasu
T
T
Hamada
T
T
Saito
K
K
Iwamasa
T
T
D000230:Adenocarcinoma / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D000293:Adolescent; D000328:Adult; D000368:Aged; D001483:Base Sequence; D002294:Carcinoma, Squamous Cell / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D002449:Cell Aggregation; D002454:Cell Differentiation; D004252:DNA Mutational Analysis; D016889:Endometrial Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D009154:Mutation; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism*; D009369:Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D009479:Neuropeptides / Q000378:metabolism; D018202:Pulmonary Blastoma / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D051176:beta Catenin / Q000235:genetics* / Q000378:metabolism
D009363:Neoplasm Proteins; D009479:Neuropeptides; D051176:beta Catenin