CRAZY THEORY TIME!!
If Law has been a medicine mastermind since his childhood and if he, by chance or force, was able to obtain his fruit powers since childhood there is a chance,slim one but still, that he took Mingos innards away from him as a whole and let them functional in a place called "the core"(at least thats what sabo is looking I´m guessing). Ok, I´ll confer that given his age this theory doesn´t hold much ground. Yet, it doesn´t rule out that the person who seems to be his mentor Cora-san had business in these regards.
It would simply fit explendid if the former heart seat was a medicine expert who took in Torao. Cora-san might have been the person in charge of Dofla´s inner safekeep until an incident happened. I base this mainly on the relationship between Corazon-heart and core. As the story progresses, strange vibes are reaching my senses.First off, Doflamingo wasn´t frozen "to the core" by Aokiji. (Buffallo said this himself) Implying that his heart was functional, which really doesn´t make much sense unless its being held elsewhere. After typing the last sentence,I must confess I´m sensing a nagato-ish storytelling from all this development; reason being that Vergo points out Laws obliviousness towards doffy's past.
Law didn´t know Doflas true story, which leaves me under the impression that the former seat of hearts will play a huge role in Doflamingos flashback.His-her Absense and Doflas resilence to death are keyed and intertwined. Moreover Why haven´t we seen Moi cheri and Kanjuro, its obviously starting to get vexing inside the port area so I expect there appearance soon enough.
All in all, I´m a supporter of the theory that all of Doflas vital organs are held somewhere else, that includes his brain, heart, lungs and what not making him tough as hell to fight against..