Is the presentation derm or GI? We recently had a pt who was addicted to certain meds and supposedly had porphyria (my first interaction with this illness.) Turns out his testing was negative. We also could not secure his records so drew labs to send out to a place that could run them, which is when the pt was un-diagnosed.
Bottom line, if the attending provider can neither document nor care for the illness, he needs to go where they can. This takes your facility out of the middle and gets the pt where care can be given, or his ruse can be uncovered, whichever is appropriate

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I would be VERY surprised if whoever the attending doc is doesn't have some clinical data verifying the illness. If he doesn't, he needs to.