Xenoma

A xenoma (also known as a 'xenoparasitic complex') is a growth caused by various protists and fungi, most notably microsporidia. It can occur on numerous organisms; however is predominantly found on fish.

In most cases the host cell and nuclei suffers from hypertrophy resulting in a change in organisation of the cell and its structure and can result in polyploid nuclei. This outcome is due to the microsporidian parasite proliferating inside the host cell. This results in a 'symbiotic co-existence' between the parasite and the host cell. This forms the xenoparasitic complex. They tend to contain numerous cellular components as well as microsporidia at different developmental stages and spores.