Pathological features of colorectal carcinomas in MYH-associated polyposis.
OBJECTIVE
MYH is a DNA glycosylase in the base excision repair pathway. Germ-line biallelic mutations in the MYH gene are associated with the development of multiple colorectal adenomas and colorectal carcinoma (CRC). A slightly increased risk of CRC is suggested in monoallelic MYH mutation carriers. The aim was to characterize the histopathological features of carcinomas from biallelics and monoallelics.


RESULTS
Clinicopathological features of 57 colorectal carcinomas from 50 patients identified in familial CRC registries were recorded. These included 16 cancers from 14 MYH biallelics; 25 cancers from 22 MYH monoallelics; and 16 cancers from 14 controls. Carcinomas in biallelics demonstrated tubular, papillary or cribriform patterns as the predominant histological subtype, and main histological groups differed according to mutation status (P = 0.0053). All biallelic cancers were low grade, with high-grade tumours more common in monoallelics and controls (P = 0.002). Synchronous polyps were observed in 75% of biallelics, 33% of monoallelics and 43% of controls (P = 0.035). Serrated carcinoma was the predominant type in 12% (3/25) of the monoallelics but in none of the biallelics or controls. MYH immunohistochemistry failed to distinguish between groups.


CONCLUSIONS
Neither pathological features nor immunohistochemistry could predict the MYH mutation status of CRCs in this study.
Department of Pathology and Laboratory Medicine, Mount Sinai Hospital, Toronto, Ontario, Canada.
A M
AM
O'Shea
S P
SP
Cleary
M A
MA
Croitoru
H
H
Kim
T
T
Berk
N
N
Monga
R H
RH
Riddell
A
A
Pollett
S
S
Gallinger
D000328:Adult; D000368:Aged; D019943:Amino Acid Substitution / Q000235:genetics; D016022:Case-Control Studies; D015179:Colorectal Neoplasms / Q000201:enzymology* / Q000235:genetics / Q000473:pathology*; D045647:DNA Glycosylases / Q000235:genetics*; D005260:Female; D018095:Germ-Line Mutation; D006801:Humans; D007150:Immunohistochemistry; D044483:Intestinal Polyposis / Q000201:enzymology* / Q000235:genetics / Q000473:pathology*; D008297:Male; D008875:Middle Aged
D045647:DNA Glycosylases; C061738:mutY adenine glycosylase