From what I can tell, the scanners cannot see anything internal within our bodies. They are looking at surface area of our clothing and of our bodies. If there are any lumps, bumps, or other things that aren't expected then we're flagged.
"If a large cyst or mass appears to stick up above the skin or body outline around it, or looks like a solid mass compared to the area around it, the scanner may reflect that, said Dr. Mahadevappa Mahesh, a radiology and public health researcher at Johns Hopkins University in Baltimore who wasn't involved in the case report."
"It's more common for patients that have been injected with or ingested a radioactive material for nuclear medicine exams to be flagged for airport screening because radiation may be detected if they travel shortly after their procedures, Mahesh added.
While smaller cysts shouldn't confuse airport scanners, it's more likely that travelers would be flagged when they have larger ones, said Dr. David Brenner, a radiology researcher at Columbia University Medical Center in New York who wasn't involved in the case report.
"If you do have a large (greater than 2 inch) external skin lesion which is located under your clothes, you would be prudent to get a doctor's note before traveling - but you still might expect a patdown," Brenner said by email."
"One female traveler with a common type of skin cyst was flagged for a hidden explosive search at a U.S. airport, her physician, Dr. Warren Heymann, notes in the report. On future trips, this woman traveled with a doctor's note explaining her condition that she could show airport security agents, Heymann said in the case report."
"The man with the hernia had a protrusion in his groin area that alarmed airport screeners. This traveler was interrogated and subjected to a genital exam, Heymann reported."
"I would suggest that people be aware that this could happen to them if they have prominent lesions on their skin," Heymann said by email.
"Having a letter from a physician noting the presence of a cyst, hernia, or other lesion might help, but understandably, the TSA agent may still wish to perform a pat down and a swipe for contraband," Heymann added. "Mutual understanding and respect should allow the screening process to go smoothly."/www.scientificamerican.com/article/airport-scanner-flags-common-cyst-as-a-security-threat/