Pseudo papillary refers to a specific histological pattern observed in certain tumors, most notably in solid pseudopapillary neoplasms. It's characterized by nests of proliferating cells that become closely packed, with cell death (necrosis) occurring in the center of these nests. This creates a rim of cells around a central space, resembling a papillary structure, but without a true fibrovascular core, hence the term "pseudo" (false) papillary.
In essence, instead of true papillae with a blood vessel-containing stalk covered by cells, pseudo papillae are formed by:
- Proliferating Cells: Rapid growth of tumor cells forming clusters or nests.
- Cellular Disintegration: Cells in the center of these nests undergo necrosis or degeneration.
- Rim Formation: The remaining cells arrange themselves along the periphery, creating the appearance of papillae.
This arrangement distinguishes it from true papillary structures, which have a central fibrovascular core that provides structural support and blood supply. The "pseudo" characteristic is crucial in distinguishing between different types of tumors and influences diagnosis and treatment strategies.
