Hepatocellular Carcinoma - Trabecular Pattern

The trabecular (sinusoidal) pattern of HCC comprises thickened trabeculae of large, polygonal, eosinophilic tumor cells, which are separated by a network of vascular channels lined by endothelium. This endothelial lining is a helpful diagnostic feature in fine-needle aspirates. HCCs lack portal tracts, Kupffer cells (CD68+), and cohesive connective tissue frameworks - this often leads to artifactual spaces between trabeculae in cytologic and surgical specimens. Note the abundant eosinophilic cytoplasm and mild nuclear atypia in this well-differentiated tumor.