Primary interosseous meningioma associated with pregnancy--case report.

The authors present the case of a 32-year-old female with a hard, bony mass on her left forehead, present for several years, which rapidly increased in size after she became pregnant. Neuroradiologically, the tumor appeared to have originated in the interosseous space, and it invaded the subgaleal and intracranial spaces as the pregnancy advanced. The tumor was explored and removed after delivery. Light and electron microscopic studies verified that it had the characteristics of a typical meningotheliomatous meningioma. Interosseous meningiomas are biologically and morphologically similar to intracranial meningiomas and must be followed carefully during pregnancy because of their potential for rapid growth at this time.