Histological overlap between colorectal villous/tubulovillous and traditional serrated adenomas

Aims To ascertain the degree of histological overlap between conventional villous/tubulovillous ( VA / TVA s) and traditional serrated adenomas ( TSA ). Methods and results A total of 180 polyps from the left colon/rectum diagnosed as VA / TVA s were retrieved randomly and reviewed by five pathologists looking specifically at luminal serration, cytoplasmic eosinophilia and the presence of ectopic crypt foci ( ECF ). For comparative purposes, 100 tubular adenomas and 80 TSA s were also examined. Twenty VA / TVA s were reclassified as TSA . Luminal serration as noted in TSA was not seen in any of the remaining 160 polyps, ECF s were noted in 55 of the 160 VA / TVA s (34%), while cytoplasmic eosinophilia (constituting <50% of the adenoma) was noted in only 10 of 160 cases (6.2%). Conclusions Ectopic crypt foci and cytoplasmic eosinophilia are encountered in sporadic VA / TVA s but not to the same extent and degree as in TSA . ECF s were found in one‐third of cases, but cytoplasmic eosinophilia is rare. The pattern of luminal serration in TSA is very characteristic and not recapitulated in VA / TVA . The occurrence of all three histological features together occurs only in TSA . ECF s are not a sine qua non for TSA and are encountered commonly in VA / TVA s. VA / TVA s often contain occasional glands typical of TSA .