Colorectal carcinomas with microsatellite instability display a different pattern of target gene mutations according to large bowel site of origin

Table 1 Histopathologic features, BAX and IGF2R microsatellite mutation status, BRAF mutation status, MMR protein expression and mutation status in the rectal and sigmoid MSI-H carcinomas from the test series

Tumor location (sample ID)	Morphology	Differentiation	Growth pattern	Lymphocytic infiltration	Mucinous	BAX	IGF2R	KRAS	BRAF	MMR protein expression	MMRgermline mutation
Rectum (T8)	Exophytic	Moderate/well	Expanding	Moderate	No	Positive	Negative	Negative	Negative	MSH2/MSH6 absence	MSH2 c.388_389del
Rectum (T20)	Ulcerated	Moderate/well	Expanding	Moderate	No	Negative	Negative	Negative	Negative	Normal	N.a.
Rectum (T41)	Ulcerated/exophytic	Moderate/well	Expanding	Moderate	Yes	Positive	Positive	Negative	Negative	MSH2/MSH6 absence	Negative
Sigmoid (T27)	Ulcerated	Well	Infiltrating	Sparse	No	Negative	Negative	Negative	Negative	Normal	N.a.
Sigmoid (T33)	Ulcerated/exophytic	Moderate/well	Expanding/infiltrating	Sparse	No	Negative	Negative	Positive	Negative	Normal	N.a.
Sigmoid (T35)	Exophytic	Poor	Infiltrating	Sparse	No	Negative	Negative	Negative	Positive	Normal	N.a.

MMR - Mismatch repair. MSI-H - microsatellite instability-high. T- test series; N.a. - not analyzed; TGFBR2, MSH3 and MSH6 mutations and MLH1 methylation were not found.

ISSN: 1471-2407