I have a RIR who is laying some really wierd looking wrinkled eggs. When I cracked them open to eat, there was some cloudy stuff - yuck. The second weird egg wasn't as bad as the first so I thought whatever it was is resolving itself, but then yesterday she laid one that was equally as strange as the first. I bought her as a pullet with two others, and either they contracted Marek's at my place or came with it, because those two died a couple of months ago and UC Davis' extension office necropsied them and found Marek's. I thought this remaining girl was now a carrier who would live with it, but could this egg situation be a symptom of Marek's?
Infectious bronchitis also can cause shells like that. Sometimes birds will have a mild case and show few symptoms so you may not even notice.
Is she a new layer? Sometimes new layers will lay unshelled or other bad eggs when they are starting out. Shriveled eggs are not a symptom of Marek's Disease, but if she has gotten Marek's, it could have affected her laying ability.
Here's a page with lots of info on egg oddities: http://www.the-chicken-chick.com/search?q=egg+oddities
I got one of those today and when I cracked it open it had a bad yolk and white cream cheese lie stuff in it. Could this be from a younger chicken or an older?