Imaging findings of Kaposiform Hemangioendothelioma in children

Kaposiform hemangioendothelioma (KHE) is a rare, aggressive vascular tumor that typically occurs during infancy or early childhood. Though several case reports have discussed the imaging findings of KHE, larger comprehensive studies are lacking. The purpose of this study was to evaluate the imaging findings of KHE in children.

A total of twelve cases of pathologically proven KHE were collected by searching our institution's pathology database for children diagnosed between January 2004 and April 2016 (6 male, 6 female; median age: 3 months; age range 7days - 18 years). CT (n=7) and MRI (n=9) findings were retrospectively evaluated. The location, morphology, enhancement, and growth pattern were analyzed.

KHEs involved various locations: superficial or deep soft tissue of the extremities (n=4); abdomen (n=3; 2 cases, pancreas; 1 case, small bowel), neck and mediastinum (n=1); chest wall, diaphragm, and pericardium (n=1); abdominal wall (n=1); and head (IAC, CP angle) (n=2). Eight of 10 cases (80%) with CT/MR findings were locally invasive and involved two or more adjacent organs. Three cases presented as well-defined solid masses, and seven were associated with infiltrative lesions of the surrounding areas with (n=4) or without definite solid regions (n=3). In nine patients with MRI, all KHEs were heterogeneous and hyperintense to muscles on T2-weighted images (T2WI), while four KHEs consisted of some regions that were nearly isointense to muscle. Eight of the 10 cases with imaging exhibited heterogeneous intense enhancement, while only one demonstrated mild enhancement. Signal voids (n=2), engorged vessels (n=1), calcification (n=3), hemorrhage (n=1), or bone changes (n=4) were infrequently observed. Four patients (33%) had Kasabach-Merritt phenomenon, and recurrence was observed in two cases.

KHEs occurred in various locations, affected mostly infants, and generally exhibited intense heterogeneous enhancement. In more than half of the included cases, KHEs were highly infiltrative and locally invasive with ill-defined margins. Awareness of these features should prompt radiologists to include KHE in the differential diagnosis for pediatric masses.