ONSC Provides Commentary on Standard of Care for Anatomic Pathologists in Cases of Delayed Diagnosis

  • August 22, 2022
  • Michael Valdez


The Ontario Superior Court of Justice’s April 2022 decision in The Estate of Mary Fleury et al v. Olayiwola A. Kassim[i] 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. 

Medical History

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 was 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.