The mysterious organ. Spectrum of focal lesions within the splenic parenchyma: cross-sectional imaging with emphasis on magnetic resonance imaging.

Incidental splenic lesions are frequently encountered at imaging performed for unrelated causes. Splenic cysts, hemangiomas, and lymphomatous involvement are the most frequently encountered entities. Computed tomography and sonography are commonly used for initial evaluation with magnetic resonance imaging reserved as a useful problem-solving tool for characterizing atypical and uncommon lesions. The value of magnetic resonance imaging lies in classifying these lesions as either benign or malignant by virtue of their signal-intensity characteristics on T1- and T2-weighted imaging and optimal depiction of internal hemorrhage. Dynamic contrast-enhanced sequences may improve the evaluation of focal splenic lesions and allow characterization of cysts, smaller hemangiomas, and hamartomas. Any atypical or unexplained imaging feature related to an incidental splenic lesion requires additional evaluation and/or follow-up. Occasionally, biopsy or splenectomy may be required for definitive assessment given that some of tumours may demonstrate uncertain biologic behavior.