Klassifikation und Beurteilung von zufällig im Ultraschall gefundenen Milztumoren - eine retrospektive Studie

Focal splenic lesions are found in less than 1% of abdominal ultrasound examinations. Despite their rare occurrence they pose a threat for both patients and doctors. Initial differentiation of malignant from benign lesions might not be feasible and consequently result in unnecessary or missed out further diagnostic workup. In the department of ultrasound diagnostics of the Philipps-University Marburg incidentally found focal splenic lesions were collected in the period of 2002 to 2019. Among those n=128 met the inclusion criteria and were retrospectively evaluated. All patients were examined by B-Mode Ultrasound and Contrast Enhanced Ultrasound (CEUS). The spleen features a pronounced vascularisation and shows long lasting enhancement, therefore being well suited for CEUS. Differentiation of malignant from benign lesions was based on histological examination in 17 cases (13%) and done with the help of follow-up imaging in 111 cases (87%). The median period of these follow-ups was 24 months. A total of nine splenic incidentalomas (7%) were malignant, while 119 (93%) were benign. Among the malignant lesions 6 cases (67%) were diagnosed as NHL. The other 3 (11% each) were diagnosed as leukemic blast infiltration (AML), metastasis (malignant melanoma) and Hodgkin lymphoma. Four out of 7 lymphomas (57%) were found to be primary splenic lymphomas. The diagnosis of malignant splenic incidentaloma was histologically verified in 7 cases (78%) and determined by follow-up examinations in 2 cases (22%). Incidentalomas of patients without a history of malignancy (n=82) as well as of patients with prior malignancy (n=42) were considered malignant in 7%. We established a classification of B-Mode and CEUS findings for greater comparability (Type I-V). Among hypoechoic tumors showing iso- or hyperenhancement during CEUS (Type I) one incidentaloma (3%) was assessed to be malignant, even though the sonographic appearance of this type is usually characteristic for benign vascular tumors. All lesions showing hyperenhancement were benign. In 19% and therefore most frequently hypoechoic lesions displaying hypoenhancement during CEUS (Type II) were malignant. No malignant lesions were found among hyperechoic lesions showing iso- or hyperenhancement (Type III) or complex-cystic enhancement (Type V). Hyperechoic lesions displaying hypoenhancement during CEUS (Type IV) were malignant in 8%.