fig4

Figure 4. At lower magnification the neoplastic proliferation presented an infiltrative extrinsic pattern of the colonic wall in the first surgical sample (A, ×120, hematoxylin-eosin stain); the neoplasm was unreactive for CK20, (note the positive control of the normal mucosa). The inset showed a patchy not uniform immunoireactivity for chromogranin-A in neoplastic elements (×240, haematoxylin nuclear counterstain)