Fig. 3
Examples of histologic disorganization and hypercellularity in a minority of carcinoids with elevated proliferation rates. a–f Illustrate a liver metastasectomy specimen with well-demarcated areas of increased proliferation associated with increased cell crowding and higher nuclear/cytoplasmic ratios (d, f) in the background of conventional nested/organoid carcinoid morphology with low mitotic and Ki-67 rates (c, e). This was the only specimen in this series where areas of increased proliferation were sharply demarcated from low-proliferative areas by H&E. g, h Illustrate specimens from lung (g) and liver (h) in which focal areas of singe cell/cord-like infiltration were intermixed with areas of conventional carcinoid morphology. Arrows in d highlight mitotic figures. Despite increased cellularity and loss of organoid architecture, none of the cases exhibited geographic/confluent necrosis; only limited comedo-like necrosis was present (h, asterisks)
