Diagnostic Certainty

Diagnostic certainty is a component of all cases and reflects how well the diagnosis has been established. It ranges from "possible" to "certain" and it is crucial that the certainty of a diagnosis is not overstated. Doing so only reduces the utility of the Vetlucent case library and undermines your own credibility as a contributor. Vetlucent is a collection of cases with high diagnostic certainty to serve as exemplary teaching material.

Please submit cases with conclusive diagnostic evidence and strive to establish the diagnosis with supporting information such as pathology reports. 

Which diagnostic certainly level applies?

It is difficult to have a dogmatic definition for each level (see below) as this largely depends on the case. A good rule of thumb is to ask yourself this:

"Would a high-end peer-reviewed journal accept the diagnosis if you submitted it as a case report?"

In other words, would a cynical and skeptical third party agree that there was no doubt whatsoever about the diagnosis? Only if your honest answer is "yes" then, and only then, can the diagnosis be considered "Certain". 

This is especially true for rare, atypical or generally unusual cases. Remembering a saying popularied by Carl Sagan "Extraordinary claims require extraordinary evidence". Before we can accept a diagnostic certainty of "certain" or "almost certain" we need you to mount a compelling case, and in such instances, it will require histology reports or slides, operative photos etc.

Feeling confident is not the same as being correct. Be extra cautious when:

• you're outside your clinical comfort zone

• the case is from a species or system you don’t routinely interpret

• you lack firsthand access to the confirming diagnosis

Diagnostic certainty levels

1. Possible (red dot)

   • the preferred diagnosis is one of a number of possible diagnoses, and although it is perhaps more likely, other conditions remain viable alternatives

   • cases like this are often not worth posting.

   • if you want to publish it anyway, you need to include a discussion on why you favor a particular diagnosis

   • be prepared for your case to be rejected for publication; that's ok, you can always keep it as one of your unlisted cases

   • possible cases are omitted from search results if the case diagnostic certainty filter is set to anything other than "All" cases

2. Probable (orange dot)

   • the preferred diagnosis is far more likely (>90%) than any alternative, but the diagnosis has not been established.

   • probable cases are omitted from search results if the case diagnostic certainty filter is set to "At least almost certain" or higher

3. Almost certain (yellow dot)

   • you have good reasons to believe the diagnosis was confirmed, but you do not have direct access to the proof and cannot upload it.

   • examples: 

     • you collected this case some time ago and have included "path proven" in the description but not the actual histology report

     • a secondary source states the diagnosis (e.g. the referral, or the treating unit or a colleague tells you the result of a biopsy) but you haven't seen the report yourself

   • imaging is almost pathognomonic, but it is conceivable that an unusual-appearing other entity could have similar appearances

   • examples:  

     • lipoma has a very characteristic appearance but it is conceivable that a liposarcoma could appear similar

4. Certain (green dot)

   • the diagnosis is 100% certain based on:

     • unequivocal or pathognomonic imaging appearance

       • remember Aunt Minnies are not always pathognomonic

     • clinical, surgical or pathological proof directly obtained from a primary source by the uploader (e.g. directly from the histology report)

   • where appropriate you should include substantiating evidence (e.g. histology report/slides, diagnostic laboratory test/values)

   • Again—"Would a journal accept the diagnosis if you submitted it as a case report?" In other words, would a cynical and skeptical third party agree that there was no doubt about the diagnosis? Only if your honest answer is "yes" then should the diagnosis be considered "Certain". 

5. Not applicable (no dot)

   • the images are not of a patient with a particular diagnosis

     • normal scan for anatomy review

     • diagrams, illustrations, or flow chart

Example cases

Check out the following cases to see how diagnostic certainty is applied:

• pyothorax (almost certain)

• pyothorax (certain) - cytology report

• inflammatory lung disease (certain) - pathology images and report