Meningiomas

Clinical and Radiological Features

Meningiomas are defined as meningeal tumors arising from meningothelial arachnoid cells, typically arising at the inner surface of the dura mater. They show a staggering diversity of locations, growth patterns, and histologic variations such that in both the neuroanatomical and histological senses they are the great mimicker of many other pathological entities.

Meningiomas account for approximately 30% of all primary brain tumors and are thus the single most common “brain” tumor, excluding glioblastoma as the most common glioma, in persons over the age of 35 years (Claus et al., 2005). In middle-aged adults, meningiomas are distinctly more common in females (Longstreth et al., 1993). Spinal meningiomas are also more common in women (Cohen-Gadol et al., 2003), accounting for almost 90% in some series among the older patients (Gezen et al., 2000).

Meningiomas are also recognized in childhood and represent the most common dural or leptomeningeal based neoplasm in this age group. Pediatric meningiomas may be characterized by large size at diagnosis, cyst formation, intraparenchymal location and high-grade histology, aggressive behavior, particularly in the clear cell and papillary variants (Perry and Dehner, 2003; Rushing et al., 2005). Unlike in adults, there is a male predilection in pediatric meningiomas. Pediatric meningiomas are also within the spectrum of postirradiation tumors.

Multiple meningiomas are a cardinal feature of NF2 and occur in half of NF2 patients (Louis et al., 1995). Forty percent of pediatric patients with meningioma have NF2 (Perry and Dehner, 2003).