Ultrasonographic features of abdominal ectopic splenic tissue

Ectopic splenic tissue may be congenital (an accessory spleen) or a result of traumatic autotransplantation (splenosis). The purpose of this study was to identify the features of ectopic splenic tissue in ultrasonography (US) scans. Selective spleen scintigraphy (with heat-denatured erythrocytes labelled with technetium 99m) was performed on 33 patients who had undergone splenectomy after trauma; the 25 (76%) for whom the results were positive subsequently underwent US. Of the 25 patients, 23 (92%) had one to five foci of ectopic splenic tissue; 62 of the 68 foci (91%) were in the left upper quadrant. US identified splenic tissue in 17 of the 25 patients (68%). All 44 foci visible with US were hypoechoic, and 33 of them (75%) exhibited acoustic enhancement or an incomplete hyperechoic rim or both. Nineteen of the foci revealed by US (43%) were smaller than 1 cm2. No criteria were found to permit differentiation of accessory spleens from splenosis. In three of every four patients who undergo splenectomy after trauma, ectopic splenic tissue eventually develops. Radiologists should be aware of this condition to avoid incorrectly diagnosing this ectopic tissue as metastasis, adenopathy or another solid tumour. US, in combination with selective spleen scintigraphy, permits a specific diagnosis without invasive procedures.