What is a shadow medically?

"Shadows" are seen on conventional X-Ray images which are 2 -dimensional and on which everything having a density which can absorb the beam produces either a clear contour, like bone, or a "shadow" on that structure meaning that another dense structure in front of it, which did not completely absorb the ray is present. Those can be completely normal, can be artifacts like skin folds whose shadow on bone can look like a fracture, jewelery or piercings projected on the abdomen, looking like items being swallowed or forgotten during past surgery, or the mamillae, whose shadow on the lung often is confused with tuberculosis or carcinoma, or it can be pathological like tumors. The solution: x-ray from another direction, CT-Scans or MRI. In case of piercings, jewelery or other questionable objects in uncommon places physicians can take the most extreme and uncommon measure of all: they eventually will talk to the patient.

The disease of many "shadow" patients is called "vomit- syndrome" (Victim Of Medical Imaging Technology)