Spontaneous meningioma in a pig-tailed macaque (Macaca nemestrina)

Abstract

We present a case of spontaneous meningioma in a female pig-tailed macaque (Macaca nemestrina) more than 24 years old. Clinically, the monkey displayed slow, weak, and insecure movements and poor vision. A tumorous mass was present at the floor of the cranial vault extending from the optic chiasm towards the foramen magnum. It compressed adjacent parts of the brain, infiltrated the sphenoidal and occipital bone, and showed transcranial expansion into the pharyngeal area. Histologically, the tumor was consistent with a meningioma displaying mostly meningothelial and some microcystic components. Since only six cases of meningiomas in nonhuman primates have been reported so far and only two of these meningiomas have been described in detail, the findings of each case should be reported to expand the knowledge base of this type of tumor. In addition, this is the first description of a meningioma in pig-tailed macaques.

Figure 1

View of the cranial base of an old pig-tailed macaque (brain removed): the meningioma was located around the hypophyseal stalk involving the optic chiasm.

Figure 2

Median cross section through the formalin-fixed skull of an old pig-tailed macaque (brain and tip of the nose removed): meningioma in the hypophyseal fossa (black arrow) and in the pharyngeal area (dashed arrows).

Figure 3

Histological photograph of a meningioma in an old pig-tailed macaque: meningothelial portion of the meningioma with islands of tumor cells separated by thin fibrous stroma. (hematoxylin–eosin, scale bar $=$ 200 $\mathrm{\mu }\mathrm{m}$)

Figure 4

Histological photograph of a meningioma in an old pig-tailed macaque: Microcystic part of the meningioma characterized by vacuolated tumor cells. (hematoxylin–eosin, scale bar $=$ 200 $\mathrm{\mu }\mathrm{m}$; asterisks: bones)