Massive intra and extracranial benign meningioma metastasizing to the lung and spine: the problem of meningiomas classification and iatrogenic metastasizing

Meningioma is a common CNS tumor and metastasis in these tumours is a rare occurrence. Malignant meningiomas are more prone to metastase. However, there are frequent case reports of metastases in atypical (grade II) and even benign (grade I), which demonstrates the somehow unsatisfying prognostic power of the current classification system. We describe an extraordinary case of a patient with a massive intra and extra-cranial, benign meningioma, metastasizing to both lung and spine. Following the report we discuss 1) some of the problems of classifying meningioma, 2) massive meningiomas and 3) the possibility of intra-operative iatrogenic metastasizing. This case is unique due to its combination of different sites of metastases, massiveness, invasive growth and benign histology. Thus it ranks among those rare but not uncommon complicated courses in meningioma which is otherwise a common benign tumor. Unfortunately the existing classification-criteria do not have sufficient power to predict such complicated courses. Meningioma e um tumor comum que raramente metastatiza, principalmente em casos de meningiomas malignos. Contudo, ha casos frequentes de metastases em casos de tumores benignos ou atipicos, o que denota evidente falha no sistema atual de classificacao desses tumores. Os autores descrevem o caso de um paciente com extenso meningioma benigno intra e extracraniano que metastizou para pulmoes e coluna e adicionalmente discutem questoes relativas a classificacao e mecanismos de disseminacao hematogenica.