Computed tomography of the spleen: how to interpret the hypodense lesion

BACKGROUND: As the largest single lymphatic organ in the human body, the spleen is responsible for central immunological and haematological tasks. Therefore, the spleen can be subject to a wide range of pathologic disorders. Computed tomography (CT) represents the most widely applied cross-sectional abdominal imaging technique and is considered the imaging modality of choice for the evaluation of numerous abdominal pathological conditions. Hypodense splenic lesions are frequently encountered on abdominal CT images. Although most hypodense lesions of the spleen can be considered benign, some findings and clinical conditions warrant closer attention to the lesion. CT offers a number of morphological criteria that can be applied to differentiate hypodense lesions of the spleen, such as a the appearance of a lesion’s borders, its attenuation, as well as the presence of calcifications or solid components. METHODS: This article reviews the most common splenic pathologies leading to hypodense appearances on CT images and illustrates the key CT imaging findings in the context of the clinical history of the patients. CONCLUSION: The key imaging findings of hypodense splenic lesions are presented in order to aid interpretation during routine evaluation of abdominal CT images. TEACHING POINTS: • Haemangiomas, congenital in origin, represent the most common benign lesions of the spleen. • Lymphoma represents the most common malignant tumour of the, usually secondarily involved, spleen. • Most hypodense splenic lesions on CT represent benign lesions that require no further work-up. • For correct interpretation, hypodense splenic lesions need to be evaluated in the clinical context.