Primary Diffuse Leptomeningeal Gliomatosis (PDLG) (WHO grade III)
Our case showed typical pathological findings of the diffuse form of primary leptomemingeal gliomatosis (1). PDLG is an extremely rare malignant neoplasm with poor prognosis and occurring due to focal or diffuse infiltration of the leptomeninges by any type of glioma without evidence of intraparenchymal involvement. The absence of parenchymal invasion suggested a possible origin in heterotopic leptomeningeal glial nests (2). The diagnosis of PDLG is usually established by autopsy (3). To date, a few more than 90 cases of PDLG have been described in the literature, mainly in adults and some of them mimicking chronic inflammatory meningitis. There is not standardized therapeutic approach for PDLG but craniospinal radiotherapy in association with multi agent chemotherapy including temozolomide may prolong survival (2).
In our case, the first meningocerebral biopsy was diagnosed as pachymeningitis because the proliferating leptomeningeal cells were GFAP negative with chronic inflammatory infiltrate associated. A second surgical leptomeningeal biopsy and PM examination were required to make an accurate diagnosis. The tumor was a leptomeningal proliferation of cells, focally positive for GFAP.
The angiotropism of the tumoral cells was probably the cause of her longstanding migraine, and the multiple brain infarcts in the advanced phase of the disease. Infarcts in PDLG were previously described in other autopsied cases and generally considered as a terminal event of the disease (4). Circle of Willis and major branches angiopathy has been described in benign conditions, such as systemic lupus erythematosus (5), tuberculosis (6) or syphilis (7); giving rise a clinical diffential diagnosis in which LCR microbiological and molecular results should be crucial. Some malignancies involving leptomeninges can develop angiotropism but it is a very uncommon event. Otherwise, primary intravascular lymphoma can appear with multiple brain infarctions (8).
Finally, both clinical and neuroimaging findings at initial presentation and also in the follow-up were non-specific, leading to the delayed diagnosis.
Contributed by Fernandez-Vega I, Saiz A, Santos-Juanes J, Piņa-Batista K, Corte-Torres MD, Astudillo A