This exam was interpreted as "Ovarian cancer with liver metastases, peritoneal disease, and malignant ascites"
It is understandable why the attending would come to this conclusion, but it is incorrect and a classic example of Type 1 thinking - pattern recognition
The scenario is as follows: Young woman with a large complex cystic pelvic mass, peritoneal disease, ascites, and liver metastases - this is metastatic ovarian cancer
We all use pattern recognition to aid in our interpretation of imaging studies and this cognitive "short-cut" helps us most of the time. However, this is one example where it can lead us astray. If you thought this was an ovarian cancer, go back to the video or static images and take another look (answer is on one of the static images). We will review the static images starting with the pelvis.
There is a large complex cystic mass in the pelvis. The characteristics are typical of cancer; large size, thickened enhancing walls and septations, and ascites. Taken by itself, this finding is suggestive of an ovarian malignancy, but ovarian is not the only type of cancer that can cause a complex cystic adnexal/pelvic mass.
There are also soft tissue nodules along the peritoneal surface (yellow arrow above), representing peritoneal disease related to the cancer. This again is a typical finding of ovarian cancer but not the only type of cancer that can spread intraperitoneally. The other cancers that commonly spread intraperitoneally include any gastrointestinal cancers (stomach, bowel, pancreas) and cholangiocarcinoma.
There are a number of liver lesions consistent in appearance with metastases. This is the first clue that the primary cancer may not be ovarian. While you can see liver metastases with ovarian cancer, it is not the common presentation. Any time I see liver metastases in a patient with a diagnosis of ovarian cancer, I go through the chart to make sure there is a tissue diagnosis. I also do not biopsy liver lesions in a patient with ovarian cancer unless there's been a good quality MRI. This has saved me from performing biopsies on hepatic adenomas and FNH, which are usually obvious on the MRI (isointense or hyperintense on pre-contrast T1-weighted images with fat saturation).
Here we are at risk of falling prey to satisfaction of search. We have made up our mind that this is metastatic ovarian cancer and prematurely terminate our search for a cause. If we are vigilant in our search pattern, we come to a significant finding that changes our diagnosis.
The image above shows a sigmoid mass with adjacent adenopathy. This is a typical presentation of colon cancer with eccentric wall thickening, narrowing (apple core), and hyperenhancement relative to normal colon. While ovarian cancer can involve the bowel, it is typically through peritoneal disease along the serosa, which has a different appearance.
This was path-proven colon cancer with a large cystic implant on the ovary, peritoneal disease, and liver metastases.
Discussion
An interesting twist to this case is that when I discussed it with the attending who read it with a resident, the attending said that they had identified the colon mass during final readout but had forgotten to alter the original resident report because they had been interrupted during review. I believe interruptions are a common cause of errors in radiology but difficult to quantify or identify in retrospect.
One of the ways to mitigate the effect of interruptions is to design your workflow and report templates to account for interruptions. My templates are empty so that if I am interrupted, I can see where I left off based on what organ systems have already been dictated. This is one of the reasons I caution against using prefilled templates.
Another strategy I want to highlight with this case is to keep an open mind and try not to come to a conclusion before you are done looking at the entire study. If there's any finding that doesn't fit with your conclusion or diagnosis (for me it was the liver metastases), consider other possibilities. And if you are vigilant with your search pattern, you would have identified the colon mass while running the colon, which you should do on every case.
