Primary pulmonary meningioma. Report of a case and review of the literature.

Extracranial meningiomas are rare outside the head and neck region. We report a case of primary pulmonary meningioma, initially detected as a radiographic incidental finding, occurring in an asymptomatic 45-year-old woman. Light microscopic examination of both cytologic and histologic preparations was typical of a classical meningioma and included such features as intranuclear pseudoinclusions, psammoma bodies, and cellular whorls. Immunohistochemistry demonstrated tumor cell positivity for vimentin and epithelial membrane antigen, as is characteristic of meningioma. Ultrastructural analysis showed interdigitating cell membranes and desmosomes, with no evidence of basal lamina, neurosecretory granules, or microvilli. On short-term follow-up, the patient is well and has no evidence of a cranial or spinal meningioma. The previous 10 cases reported in the literature had similar characteristics, including a tendency toward occurrence in middle age to older women, asymptomatic presentation, peripheral lung location, and morphologic features. Finally, other conditions in the differential diagnosis and possible histogenesis are discussed.