Patterns of neuroaxis dissemination of gliomas: suggestion of a classification based on magnetic resonance imaging findings.

BACKGROUND

Local invasion is the hallmark of malignant glioma dissemination. Leptomeningeal dissemination, a serious complication of malignant gliomas, has been increasingly observed. To correlate the physiopathologic mechanisms and the magnetic resonance imaging patterns of neuroaxis dissemination, a classification of malignant glioma dissemination is proposed (Instituto de Neurologia de Curitiba Classification).

METHODS

This classification includes the following patterns of dissemination: leptomeningeal (type I), nodular (type Ia), diffuse (type Ib); subependymal (type II); satellite (type IIIa, IIIb); and mixed (type IV), combination of 2 or more previous types. Of 138 patients with histologically confirmed gliomas treated between 2000 and 2004, 10 presented neuroaxis dissemination and were evaluated.

RESULTS

The distribution of dissemination patterns was as follows: subependymal, 4 of 10; diffuse leptomeningeal, 1 of 10; nodular leptomeningeal, 1 of 10; and satellite, 4 of 10. Mean interval between primary tumor and dissemination was 4 months. The most frequent glioma dissemination risk factor was entering the ventricular system during surgery.

CONCLUSIONS

Improvements in our diagnostic imaging capabilities have contributed to a better understanding of the patterns of malignant glioma dissemination. Using this information, we present a useful classification scheme, applicable to patients with neuroaxis dissemination, which will help standardize future discussions aimed at understanding these patterns of tumor spread.