When the Lesion Should Be There, but Isn't.

Diagnostic imaging plays a prominent role in the evaluation of numerous medical conditions, ranging from suspected infections to assessment of the acutely injured patient to staging malignancies and numerous other conditions, both common and rare. Imaging can be a very powerful tool in the diagnosis of medical disorders and plays a major role in the assessment of therapeutic response as well. It is common in practice for imaging studies to provide findings that may corroborate the clinical or laboratory impression of a disorder, allowing a presumptive diagnosis and institution of therapy, often circumventing the morbidity and even mortality that could be associated with an invasive tissue confirmation of a suspected diagnosis. Furthermore, imaging may occasionally detect entirely unsuspected disorders in minimally symptomatic, or even entirely asymptomatic, patients, the latter typically in the context of screening for malignancies. However, on occasion, imaging may fail to disclose a condition that "should be there" on the basis of findings at clinical and/or laboratory examination; this situation is particularly true when imaging fails to reveal abnormalities in the context of a suspected paraneoplastic syndrome. In this circumstance, there may be few, if any, alternatives to approach diagnosing such patients, and the appropriate treatment of these patients becomes exceedingly difficult. Such a situation can even lead to unnecessary, perhaps even inappropriate, interventions. In this circumstance, careful reconsideration of the imaging findings is paramount for correct patient management.