CPC: Advice From a Dermatologist-Dermatopathologist

In dermatology, biopsy is one of the most important tools for securing a diagnosis and therefore a treatment plan for the patient. Histopathologic findings are critical to narrowing down the diagnosis, and clinicopathologic correlation (CPC) is the link between the dermatologist and dermatopathologist. However, there may be times where the clinical diagnosis and histiopathologic interpretation do not agree, and knowing how to handle those in- stances can help avoid delays in care for patients.

At the American Academy of Dermatology Summer Meeting 2021 in Tampa, FL, Kiran Motaparthi, MD, FAAD, opened the meeting on Thursday, August 5th, with the presentation “Lessons in CPC.”¹ During the presentation, Dr Motaparthi discussed how to troubleshoot when the histopathologic interpretation does not match the clinical presentation, described heuristic and analytic diagnostic approaches in dermatopathology, and highlighted several cases in which errors can be clues to the correct diagnosis.

Dr Motaparthi is associate professor of dermatology, director of the residency program, and director of the dermatopathology at University of Florida College of Medicine in Gainesville, FL. In an interview with The Dermatologist, Dr Motaparthi shared how dermatologists can improve their CPC and their communication with their dermatopathologist.

For those who were unable to attend the 2021 AAD Summer Meeting, can you provide an overview of your presentation?
Yes, I would be happy to share a little about CPC. Traditionally, CPC rests upon a dermatologist’s ability to interpret and apply findings that are reported by pathologists. Similar to dermatology, dermatopathology is not a perfect science. Even if the histopathologic interpretation is not correct, we as dermatologists are still responsible for getting the right diagnosis for our patients.

My AAD Summer Meeting presentation was geared toward dermatologists and discussed diagnostic approaches in dermatopathology and in dermatology. I used several high-yield examples to highlight potential biases and to help listeners apply this information to their own practices. Ultimately, the goal of the talk was to help dermatologists prepare for clinical scenarios that are prone to pitfalls and to support CPC in challenging cases.

What are maybe some of the key presentation takeaways that a dermatologist could implement into their own practice right away?
I will start with diagnostic errors. Diagnostic errors are worth studying, because they are the second most common cause of nonprocedural adverse events in dermatology. They contribute to more than 30% of malpractice claims. As a takeaway, these errors frequently result from a lack of CPC, or essentially for taking the pathology report at face value rather than adding an additional layer of interpretation.

Another takeaway is that most diagnostic errors in dermatology and dermatopathology are due to faulty information processing. The majority are errors in cognition, but some are also due to perception. Cognition and perception are closely related, but they are distinct. Perception is where we process visual stimuli and filter it out, producing what we ultimately see when we examine a patient or slide. Cognition shortcuts that help us make diagnoses quickly and efficiently as well as conscious checklists to analyze a case methodically.

Another one is about metacognition, which is thinking about how we think and avoiding uncritical thought. It lets us become aware of our blind spots to understand our biases and ultimately avoid potential errors. In short, metacognition lets us reach diagnostic expertise.

Overall, I hope what people took from this talk was that we should not hide from errors. We should recognize bias and then share and teach how this influences diagnosis. This can help clinicians transform these interpretive errors into diagnostic clues that help them in their daily work.

What would be your top recommendation for improv- ing communication between a dermatologist and their dermatopathologists?
A good working relationship and open lines of communication are always helpful in supporting accurate diagnosis. Clinical images have also been shown to increase diagnostic accu- racy for tumors and rashes. Those are good ways to support communication between dermatologists and dermatopathologists.

I still think the requisition form is the most important and underused method of communication. We know that less clinical information provided on requisition increases the likelihood of the descriptive or nondiagnostic pathology report and can lead to errors. To be clear, providing sufficient clinical information or context or description does not equate to a lengthy differential diagnosis. In fact, when you submit a longer differential, it does not improve your accuracy. Diagnoses listed in a clinical differential diagnosis on a requisition form should be specific, prioritized in order of likelihood, and limited in number to no more than three or four. After that, you can also provide additional context, history, and descriptive terms to convey what you are seeing clinically to the pathologist.

One more note, because I have seen this come up from dermatologists from time to time, is a concern that additional clinical information or sufficient information will bias the dermatopathologist and create error. That is not correct. Clinical or dermoscopic images, clinical history, and description improve accuracy much more often than they produce error.

Are there any resources that might be helpful for a dermatologist looking to improve their own knowledge of dermatopathology?
There are many great texts, online resources, and study guides that are great and widely available. For example, the AAD offers the MyDermPath+ app, which lets you rehearse the approach to dermatopathology. In order to apply that knowledge, you have to be doing it in practice.

The most helpful thing is to learn from the actual patients that you are seeing and the biopsies that you are performing. Communicating with your dermatopathologist more frequently can be beneficial as well. Even reviewing your own slides after they are signed out by your dermatopathologist can be incredibly helpful. There is no problem with requesting those slides for review for your own edification, and it will also help your patients. In reality, dermatologists are expected to do that. It is not done commonly now because our siloed workflows. However, it was intended that before surgery was performed, the dermatologist should have reviewed the slides. I would like to suggest that before you choose to initiate systemic treatment on someone for a chronic condition, review the slides to see what was found, especially when things are not completely making sense. It is not a new technique that we need to employ, but rather something that we need to get back to and learn from over time. What you learn from pathology can be applied to everyday practice.

Are there any other thoughts that you want to share?
Remember that the pathology report is not like any other laboratory result or chemistry panel. It is an interpretation, an opinion. Dermatopathology is subject to the same biases for diagnosis as clinical dermatology.

To become a successful diagnostician in dermatology requires a working knowledge of dermatopathology and an understanding of what microscopic descriptions mean. In many cases, the true diagnosis is not the diagnosis that is listed in your initial clinical notes as a dermatologist or in your initial pathology report as a dermatopathologist—that is what we call the final working diagnosis. This true diagnosis is seen later based on careful CPC and follow up. That is a concept that is less tangible than a lot of what we do in our workflows.

The impression people should take away from my presentation is that we are aiming to get a working diagnosis for the patient that is real and actionable and that helps the patient more than anything else. The working diagnosis does not come out of a standardized workflow where you simply perform a biopsy, take the report at face value, and then accept that diagnosis as final and permanent on behalf of the patient. The process is harder than that, and I want to share that with people.

Overall, understanding bias, diagnostic pitfalls, and dermatopathology can reduce error and make you a better diagnostician and hopefully a master clinician one day.

Reference
1. Motaparthi K. Lessons in CPC. Presented at: American Academy of Derma- tology Summer Meeting 2021; Tampa, FL; August 5-8, 2021.