Abstract
Try approaching each case report you read like a detective story. Think about the strength of clues to diagnosis, decide if there are red herrings that might mislead thinking and, most importantly, consider whether you would have done anything differently.
There is a book by Lisa Sanders called Every Patient Tells a Story (Figure 1). It’s a great read. The premise of the book is that we can learn something from every patient we diagnose and treat — sometimes about the disease condition, sometimes about how we engaged in making decisions about diagnosis and sometimes how we got it all wrong! The learning process from feline case reports is no different. Each case has a story to tell, even if the story is not complete or perhaps misdirected by faulty thinking. Because they concern the individual animal, case reports tend to be easy to relate to — one can imagine oneself in the shoes of the treating veterinarian. This may be why case reports often stick in our minds more than the findings of case series or randomised controlled trials. The key is to use the story to improve how you diagnose and treat subsequent similar cases.
We can learn something from every patient we diagnose and treat
In this issue of JFMS there is a case report by Annie Lo and colleagues from the University of Pennsylvania concerning an adverse outcome in a cat following kidney transplantation. 1 When reading a case study such as this, try approaching it like a detective story. Think about the strength of clues to diagnosis, decide if there are red herrings that might mislead thinking and, most importantly, consider whether you would have done anything differently. Now, those of you who adore crime fiction know that fictitious detectives have different thinking styles, and this is no different for the veterinarian. We’re sure that some JFMS readers fancy themselves as a Harry Bosch or Bobby Goren when diagnosing a case; others may like to approach the task more like Sherlock Holmes. Whatever your thinking style, we implore you to be an active reader of this case report, and consciously and continually ask yourself questions, as only then will you get the full benefit from this exercise. Part of this active reading process is to accept that the story will not be complete and that some facts may have been misinterpreted or over-interpreted — this is the nature of treating cases in the real world, where, for example, owners will not always be able to afford every test. By accepting this, the reader is not being over-critical. Rather, they are adopting the good scientific principles of scepticism and open-mindedness. If you scrutinise case studies in this way, you will get more out of your reading, and the details are more likely to stick in your long-term memory. That’s why large hospitals have journal clubs and ‘grand rounds’ — to encourage people to hone their cognitive skills related to diagnosis and treatment, and to be analytical when hearing or reading information related to the case.
The case report by Lo and colleagues is not complete, nor is it perfect in how it manages interpretation of diagnostic clues, but it does have a useful story to tell. Moreover, all single animal case reports can be springboards for more detailed investigations and should raise more questions than they answer. This case report is no exception.
So, when reading this article, you should be asking ‘What are the big unresolved issues in the present case?’ To guide you in this respect, consider the following questions.
Given the state of the cat at initial presentation, could it have had the opportunistic infection prior to the transplant, which then worsened as a result of immunosuppression? In other words, although the conventional wisdom is that opportunistic infections develop as a consequence of immunosuppressive therapy following transplantation, was it possible that a low grade mycobacterial infection was present in the kidneys, or in the bone marrow, prior to transplantation?
What was the cause of the cat’s renal insufficiency in the first place? The work-up of the renal disease leaves more questions unanswered than answered. For example, why wasn’t a biopsy of the native kidneys done prior to, or at the time of, the transplant to assist in assessment? Why were the renal ‘cysts’ there initially on imaging, but not subsequently? Could the ‘cysts’ have been foci of pyogranulomatous inflammation rather than cysts? In hindsight, collecting material from these ‘lesions’ might have been informative, given that cysts in small kidneys are not really consistent with autosomal dominant polycystic kidney disease.2,3 Should the sad demise of this cat have been followed by a necropsy to better understand the original kidney disease and to further assess the opportunistic infection? Definitely, but likely the owner did not give permission. Failure to do a necropsy, although understandable, hinders the advancement of knowledge.
What was the cause of the anaemia? Was it regenerative or non-regenerative? What was the cause of the thrombocytopenia? Could both have been referable to systemic mycobacterial disease with involvement of the bone marrow prior to transplantation? Could this have been the precursor to the mycobacterial osteomyelitis affecting the right hip joint?
Would knowing which species of Mycobacterium was involved have helped understand the pathogenesis better? Typing would have certainly added to our understanding of the development of such infections after transplantation and immunosuppression.
The truth is, we will never know exactly what happened with this cat prior to transplantation. And it is such a sad case because so much effort and expertise went into the management of the patient. It is exceedingly difficult to successfully treat opportunistic mycobacterial infections in renal transplant patients receiving drugs like cyclosporine A and prednisolone, whether they are cats 4 or humans. Perhaps this cat was destined not to do well, but reflecting about each step in the diagnostic and therapeutic pathway is a very necessary process to ensure that the next atypical feline patient receiving a renal transplant has a better chance for survival.
We hope you enjoy reading this case report and we hope we have convinced you that asking valid questions about any case you diagnose or treat, or any case report you read, is the way to become a better clinician.