Fig. 15

Dangerous halo in a 58-year-old male patient with metastasis of non-otherwise specified (NOS) adenocarcinoma of the colon treated with 6 cycles of FOLFIRI and cetuximab. The patient had an objective response. Preoperative MR imaging performed after chemotherapy showed an 80 mm lesion in the left liver. On diffusion-weighted image, the periphery of the tumor showed high signal intensity (a) and a low apparent diffusion coefficient (b) (white arrow). The lesion showed rim enhancement on a contrast-enhanced fat-suppressed gradient recall echo T1-weighted image obtained during the hepatic arterial phase (c) (white arrow) consistent with the presence of peripheral remnant tumor cells. There was progressive enhancement of the central part of the lesion on delayed (3 minutes) phase (d) (white arrow) corresponding to central fibrosis deposition. Gross pathology (e) confirmed the presence of central necrosis with bands of fibrosis (black star) and of a polylobated peripheral crown of tumoral glands (white stars) corresponding the dangerous halo. Histology (f) showed viable tumor glands (T) infiltrating the surrounding liver parenchyma (Li) with central necrotic (N) and fibrotic (F) changes