By Michael Valdez
The Ontario Superior Court of Justice’s April 2022 decision in The Estate of Mary Fleury et al v. Olayiwola A. Kassim is a noteworthy one. Not only does it provide a modern case study of the application of the common law principles surrounding delayed diagnosis, but it also provides new guidance regarding the standard of care, specifically, the standard of care for anatomic pathologists.
On October 31, 2015, Mary Fleury underwent a laparoscopy for a suspected small bowel obstruction. During this procedure, the surgeon noticed “diffuse seeding of the parietal peritoneum” which was suggestive of metastatic disease. The surgeon took samples of the peritoneal tissue and ascitic abdominal fluid and sent them to the pathology lab for examination.
On November 9, 2015, Dr. Kassim, Chief of Pathology and Director of Laboratory Services at the West Parry Sound Health Centre (the “defendant”) examined the tissue removed during this procedure and found a tumour mass infiltrating the wall of the terminal ileum, which he diagnosed as an adenocarcinoma ex goblet cell carcinoid tumour. The tumour encompassed the lower end of the cecum, where the appendix should have been. The defendant also diagnosed cancer in the omentum.
After these cancer diagnoses, the defendant and his team began investigating the origin of Ms. Fleury’s cancer. The defendant reviewed data from Ms. Fleury’s previous hysterectomy and oophorectomy at Soldiers’ Memorial Hospital in 2011, as well as from her appendix removal at West Parry Sound Health Centre, also in 2011. The defendant was surprised to discover that he as the pathologist who examined Ms. Fleury’s appendiceal samples during the latter procedure. When he discovered this, he ordered the pathology slides from the hospital and re-examined them.
The defendant noticed that the 2011 appendiceal slides contained evidence of cancer. On November 25, 2015, the defendant amended his original 2011 diagnosis to reflect this. A review panel of three pathologists from Mount Sinai’s gastrointestinal pathology consultation service examined both the 2015 and 2011 samples and agreed with the defendant’s assessment.
Cancer Progression and Lawsuit
Sadly, Ms. Fleury’s cancer progressed relatively quickly at this point, and she died on November 26, 2016, at the age of 45. Ms. Fleury’s estate then brought legal action against the defendant for failing to notice the cancer in 2011.
While both parties agreed that the defendant owed Ms. Fleury a duty of care, they disagreed as to whether the defendant breached the standard of care expected of a similarly situated anatomic pathologist, when he failed to identify the cancer present in Ms. Fleury’s appendix in 2011. There was also disagreement as to whether a breach, if it occurred, caused or contributed to the death of Ms. Fleury.
The Role of the Anatomic Pathologist
The court heard evidence from expert witnesses from both sides regarding the work of anatomic pathologists in examining samples and diagnosing diseases. However, the court found that the plaintiff’s expert was much more credible than that of the defence.
Using the information from their review of the evidence, the court determined that the standard of care expected of an anatomic pathologist includes the following:
1. An anatomic pathologist must ensure that any specimen slide they are examining has been prepared appropriately and is suitable for examination;
2. If the pathologist determines that a slide is unsuitable for examination, they are expected to request that further slides be prepared;
3. Once they receive a slide, they are expected to carefully review the slide to determine if they observe any abnormality, including evidence of cancer;
4. This careful examination is expected to include a gross visual inspection, a general inspection at a low level of magnification and then a closer inspection at higher levels of magnification; and
5. Where a pathologist identifies an abnormality, including possible cancer, they are expected to investigate further and provide a diagnosis based on their findings.
Applying these principles, the court found that the defendant did not meet the standard of care expected of an anatomic pathologist when he reviewed Ms. Fleury’s 2011 slides. Specifically, he did not examine Ms. Fleury’s 2011 slides with the care and expertise expected of a normal, prudent anatomic pathologist with the same level of experience and standing. This was largely because the court accepted evidence from the plaintiff’s expert that suggested that the cancer contained in Ms. Fleury’s slide was obvious at a low level of magnification and should have been noticed even by an anatomic pathologist with basic training, and certainly by one with the defendant’s years of practice and experience. For this reason, the court also concluded that the defendant’s failure to identify Ms. Fleury’s cancer in 2011 could not possibly have been excused as a mere error made during the exercise of clinical judgement.
All arguments that the defendant could not see the cancer due to possible overstaining of the slides were rejected, since it would have been the defendant’s duty to order new slides anyway. The argument that he could not identify the cancer due to the amount of inflammation present in the sample was also rejected. While the court sympathized with the difficult position of the defendant, it called this latter reason “an after the fact justification when faced with the harsh reality that he missed something that he should have seen” 
Once again accepting the evidence of the plaintiff expert witness, the court found that the defendant caused or contributed to Ms. Fleury’s death by failing to diagnosis her in 2011. The court held that had Ms. Fleury received the definitive treatment for appendiceal cancer, her five-year risk of recurrence would have been less than 30%. In other words, it was more probable than not that early treatment would have meant that she would be alive today.
Conclusion and Takeaway
In accordance with the above findings, the court ruled in favor of the plaintiffs. As tragic as this case is, patients can take solace in knowing that the guidelines for anatomic pathologists in the review and diagnosis of medical conditions are now much more legally defined. Anatomic pathologists can also rest easier as they too now have firmer guidance regarding how they should approach the medically and legally significant task of reviewing samples and diagnosing patients.
 Estate of Mary Fleury et al v. Olayiwola A. Kassim, 2022 ONSC 2464 (CanLII), https://canlii.ca/t/jnt7z
 Ibid at para 92.
 Ibid at para 93.
 Ibid at para 101.
 Ibid at para 102.
 Ibid at para 103.
 Ibid at para 220.