Two ugly gastric polyps

These two antral polyps look very different. That's because one is a polypoid cancer and the other is an innocent hyperplastic polyp. 
WHICH IS WHICH? 

■ A is malignant

Yes! A was poorly differentiated gastric carcinoma!

■ B is malignant

Surprisingly, B is actually the innocent hyperplastic polyp

explanation

Most (73%) thought that the hyperplastic polyp (polyp B) was the malignant one. Although large, the angry red colour and white spots are both strongly suggestive of a hyperplastic polyp. 

Interestingly, in both cases, the patient presented with anaemia.  Of course, when the patient undergoes the endoscopy because of anaemia, any gastric polyp should be viewed with suspicion.  
 
Although the lack of surface crypts was disconcerting, as polyp A did not seem to be firmly attached, it was removed as a single fragment (of course). Histology confirmed that the lateral and deep margins were clear and there was no lymphovascular invasion (LVI).  

In the subsequent 'cancer meeting', it was pointed out that 'poor differentiation' may be considered an indication for surgery. This would indeed be the case elsewhere in the GI tract.  However, in the stomach, poor differentiation 'on its own' (clear margins and no LVI) is 'allowed' provided that margins are clear, there is no invasion into the deepest layer of the submucosa and, most importantly, there is no LVI.  Emerging data highlights LVI as THE MOST IMPORTANT predictive factor anywhere in the GI tract. 
 
The original ‘Japanese Standard Gastric EMR criteria’ gave the go-ahead for resection of well differentiated cancers up to 2cm provided that there was no surface ulceration.   Nowadays, most of us would apply the 'Japanese Extended criteria’ which allows us to attack well differentiated EGC's up to 3cm in size even if there is some superficial ulceration of the surface.  Pertinent to this case, the extended criteria also allows us to attempt to resect poorly differentiated cancers up to 2cm provided that there is no surface ulceration.