Is there any published research which attempts to establish a possible link between extreme patriotism and institutionalized racism? What do they conclude?
While there are not any studies, at least that I know of, that directly link extreme patriotism and institutionalized racism there are multiple studies which links conservatism to patriotism/loyalty towards the in-group and a higher dislike and distrust of out-groups. We could then deduct, but not with any certainty, that racism stems from a dislike and distrust of out-groups.
I would be very cautious though when talking about this because a dislike or distrust of an out-group A) Does not directly relate to racism B) Has shown to have genetic reasons as to why an in-group would dislike or distrust an out-group.
With that said the link below goes to a study that shows how people who are conservative are more loyal and in-group based. http://web.ebscohost.com/ehost/detail?sid=89be3139-cbd6-4c9d-8137-faa4696592e6%40sessionmgr14&vid=1&hid=15&bdata=JnNpdGU9ZWhvc3QtbGl2ZSZzY29wZT1zaXRl#db=pdh&AN=psp-96-5-1029
This link goes to a study that explains why certain in-groups would have a distrust of out-groups. The intention of this study is to show how living conditions may have genetically effected humans into having a distrust or dislike of an out-group but within the study it states how conservatives are more likely to have these feelings. http://onlinelibrary.wiley.com/doi/10.1111/j.1469-185X.2008.00062.x/full
The logic behind this would be that from an evolutionary standpoint it was beneficial at times to be distrusting of out-groups. Because genes do not simply disappear but tend to linger this distrust still remains while the reasons for the distrust may still not be there. This answer may be more biological based then you hoped but it is a possible answer but should definitely not be interpreted as a fact or truth, it is solely a possible explanation.