Physician here. Relax - it means nothing. Literally. It’s the doctor equivalent of “sincerely yours” at the end of a business letter (are you REALLY saying you sincerely belong to the letter recipient when you write that phrase?). All patients are either “very interesting” or “very pleasant” in doctor-to-doctor correspondence. After all, it wouldn’t do to thank another physician for referring this “very routine” or “extremely boring” or “really nasty” patient (even if those things are the truth!).
heck, I had that exact remark (well, the “unremarkable”) about a CT scan of my sinuses.
Yep, it’s down in hard black and white that my head is unremarkable :smack:.
I’ve seen a couple of such letters which said “thank you for referring this nice woman”. Huh. Guess my inner bitch wasn’t showing that day 
I was very happy to hear at the most recent followup with my hematologist that all my blood test results were, and I quote, “boring.” He was also happy that I was immediately excited to hear them described as such.
Well, that just deflated my balloon. 
Nurse here. Ditto what the physician said; these are all common phrases and are used automatically.
One of my own reports indicated that I was a “very pleasant, obese man.” Cripes, talk about handing you a compliment then kicking you in the nuts.
A bit OT, but this is one of my favorite entries that I have run across: “Papal edema noted”. What they meant was the optic disc was enlarged (papilledema), not that the pope was swollen.
When I first started in pediatric cardiology, I was startled to hear on a dictation tape what I thought was “painted frame in a valley”. 
Heh, I have a condition that seems to occur on the order of one in a million births. Even seasoned specialists have been known to get a bit excited when I show up in their office. “I read about that in med school, but I’ve never seen it.”
Yep. Seriously.
I hear you, whiterabbit. Sometimes they get excited over my meds too. “So how do you feel that one works for you?” “Oh, I’ve read about that - is it effective?”
Especially if they’re in a different specialty - they don’t want to talk about why I’ve been referred, rather they like to talk about my other conditions. Oh well, it’s good to spread the knowledge around, I guess.
“Very interesting” is code for…thank you for referring this patient to me and please refer many more in the future.
Yeah, on my psychiatry rotations we were trained to make note of this. I think it’s because psychiatric patients quite often have lived a hard life that tends to age you (drugs/alcohol/smoking, poor sleep habits, homelessness) and it can give you a sense of how the person is functioning if they look disheveled and haggard in comparison to a youthful looking, well put together person.
I agree with everyone who noted that “interesting patient” is a standard pleasantry that doesn’t mean much. It’s often used for totally routine, boring patients.
I generally reserve the term “pleasant” for patients who really are, though my threshold is low - to me it just means the patient was cooperative and polite. When a patient is “difficult”, I do make note of it in the chart just in case it ever becomes an issue for me that I did not document some info or exam finding on the patient due to their lack of cooperation or such.
Nobody I’ve ever known actually does the Seinfeld thing of using the patient’s past documents to screen out the obnoxious patients. 
In certain settings where difficult patients tend to be frequent (like in the emergency department and psychiatry) word does often get around about which frequently seen patients are hard to work with, but they still get seen just like everyone else.
One of my favorite medical acronyms is LOLFDGB - little old lady: fall down, go boom. Also, SOCMOB - standing on corner minding own business, the usual position stated when a patient has been assaulted by “Sumdood” (some dude).
“Mr X is a difficult historian”
“Mr X gave a convoluted and rambling history”
“Mr X’s history was challenging to interpret”
“It was problematic framing Mr X’s narrative of his symptoms into a differential diagnosis”
All of them mean the exact same thing, but Mr X may feel quite differently about each doctor who wrote them if he reads his chart!
FWIW, the standard thing here is to thank someone for their kind referral, or that you reviewed their patient in a clinic (no qualifiers).
I therefore use “interesting” to genuinely mean that the patient was of interest, “unusual” means that I was really interested and “pleasant” means that they were coherent and co-operative.
If they were difficult you try and spell it out in neutral language
“Mr X has done extensive reading on the internet and is very keen for us to try ZOBISOL. As you know this treatment is not used in our department. I re-iterated our department’s standard treatment protocol and the rationale behind it and Mr X agreed to use the interval until our next appointment to consider his options”.
“Ms Z feels that there has been an unacceptable delay in reaching a diagnosis, I explained that unfortunately we are still awaiting the results of our investigations and that in the meantime we have outruled any serious cause of her symptoms”
rather than
“Mr X has been taken in by some nutbar on the internet” and “Ms Z is an impatient brat with hypochondria”…but that’s not exactly rocket science.