Experience is a Janus-faced character which can both affect insight and expertise and be molded by them. For many situations, increasing familiarity breeds enhancing ability. Many of you are aware of Malcolm Gladwell’s notion that virtuosity in a particular occupation requires 10,000 h of labor to learn its techniques superbly and master its unique corpus of knowledge. True enough when a questioning spirit keeps the mind alert to rare events and their management and repetitive tasks become imprinted in muscle memory or thought processes.

But not uncommonly, experience may not be enlightening when the encrustations of tradition, bias or unquestioning certainty compromise one’s ability to appreciate variation or novelty. Distracted by other attentions, routine work may become so automatic that one becomes hidebound, unable to sense a new finding or welcome a new approach.

This double-edged sword now affects not only individuals but the whole domain of practitioners who mindlessly accept a dogma even when obvious facts come on the scene but are not recognized. The Emperor Who Has No Clothes may be appearing in a radiology department near you if you are not aware.

This long-winded introduction is a lead in to an observation so simple, so obvious, so deliciously trenchant that it was missed by all of Radiology for nearly 85 years, until recognized by one former resident of mine in the early 1980s. I refer to the recognition of a nipple shadow as being distinct from a lung nodule on conventional frontal radiography of the chest. The fact that that once new (now decades old) observation is still not part of the canon of pulmonary imaging teaching is emblematic of the persistence of a notion long held, even if it is clearly wrong.