The Shadow That Wasn't: A Benign Artifact Turned Biopsy
A real-world example of Pareidolia in action
Context
A mid-sized community hospital's radiology department handled a high daily volume of outpatient CT scans and relied on visual readouts with limited time per study. Many scans came from outside facilities with varying image quality, and radiologists often made rapid judgments under time pressure.
Situation
A 56-year-old woman underwent an abdominal CT for vague abdominal pain. During a busy shift, a radiologist noticed an irregular dark area near the liver edge on a single axial slice and documented a 'suspicious focal lesion' that was recommended for tissue diagnosis. The finding was subtle and only present on a few low-contrast images.
The bias in action
The radiologist's visual system and experience prompted them to detect a familiar lesion-like pattern in the grainy image — interpreting random noise and an imaging artifact as an organized pathological structure. Rather than labeling the finding as indeterminate or ordering confirmatory imaging, the radiologist's report framed it as likely neoplastic, giving clinicians a story to act on. Colleagues later noted the shape evoked the classic outline of a small mass, amplifying the confidence in the impression despite limited supporting evidence.
Outcome
The patient underwent ultrasound-guided core biopsy two weeks later; pathology returned benign inflammatory tissue. The procedure resulted in a minor hemorrhage requiring overnight observation and extra imaging. A retrospective peer review identified the original CT irregularity as a partial-volume and beam-hardening artifact related to a surgical clip in adjacent tissue, not a true lesion.