Spontaneous isolated lipoma of the choroid plexus in the baboon.

A case of symptomless, solitary lipoma of the choroid plexus is described. The tumour was found in the left lateral ventricle of an adult female baboon (Papio papio) in the course of post-mortem examination. Routine histological investigation showed that the tumour was composed exclusively of characteristic adipose cells with scarce collagen septa and without other hamartoma-like constituents, such as glial cells, neurons, cartilage or muscle fibres. The tumour mass was lined by a typical single layer of cuboidal cells; no calcifications were observed either inside the tumour or in the adjacent periventricular regions. This case is reported in view of the rarity of such tumours of the choroid plexus in man and animals, and to throw light on their possible origin.