Neoplastic cell palisades and perinecrotic palisades in veterinary neuropathology

Neoplastic cell palisades (also referred to as palisades or primary palisades) and perinecrotic palisades (also referred to as secondary palisades or pseudopalisades) appear in distinct sets of neoplasms. Neoplastic cell palisades consist of elongate neoplastic cells that form parallel rows, whereas perinecrotic palisades are oriented transversely to the margins of necrotic foci. Each of these morphologic patterns is formed by different mechanisms. Palisades are associated with intrinsic morphologic features of a neoplasm, whereas perinecrotic palisades reflect a response of neoplastic cells to tissue hypoxia and necrosis. The interchangeable use of these terms may contribute to the occasional confusion as to which is more appropriate in specific circumstances. Here, we briefly review the nature of neoplastic cell palisades and perinecrotic palisades and their occurrence in nervous system neoplasms of domestic animals. We also advocate for consistency in terminology and encourage the use of the terms palisades and perinecrotic palisades when addressing these changes in domestic animal neoplasms.