Do you know your Kudo crypt patterns?

This polyp was found in the transverse colon of a 60 year old man.
WHAT IS THE LIKELY HISTOLOGY OF THE LESION?

■ Serrated polyp

Crypt openings look a little serrated but nothing else does!

■ Adenomatous polyp

This is not an adenomatous crypt pattern!

■ Hamartomatous polyp

When in doubt, it's hamartomatous !

■ Malignant polyp

The crypt pattern is too organised and regular for cancer!

explanation

Sadly, an intimate knowledge of the Kudo crypt patterns doesn't help you here! Adenomatous polyps should be covered with one of the following; 

• Small round crypts of a TA+HGD
• Slit-like crypts of a TA+LGD
• Gyrate crypts of a TVA

Of course, you have the 'villous adenomas' which are covered by finger-like extensions (and no crypt openings). 

In this case, the closest match is of a serrated polyp, which have wide open crypts with a somewhat jagged outline. However, apart from the crypt openings, there is nothing on this which looks like a serrated polyp!  

If you can't see a crypt pattern, the lesion is likely to be malignant. Conversely, if the lesion does have crypts but still doesn't look familiar, its either a hamartomatous polyp or, perhaps less likely, a 'Traditional Serrated Adenoma'.  

This lesion turned out to be a hamartomatous polyp. Why a 60 year old man would grow a hamartomatous colonic polyp remains a mystery !