Papillary carcinomas are made up of varying quantities of neoplastic papillae and follicles (Fig. 16.7). The papillae consist of elongated, branching fibrovascular cores covered by a single layer of epithelium. The follicles, however, may contain eosinophilic colloid or appear empty. The nuclei of the papillae and follicles in approximately sixty per cent of the tumours are characteristically empty-looking, with a prominent rim due to linear condensation of chromatin against the nuclear membrane. These nuclei are described as having a ΓÇÿground-glassΓÇÖ appearance and are large, misshapen, and overlapping. Two other characteristic appearances in occasional nuclei are the presence of a clearly circumscribed vacuole of intranuclear cytoplasmic invagination and nuclear grooving that resembles a coffee bean.
