Secretory meningioma with KLF4 K409Q mutation in collision with glioma.

AIMS: The simultaneous occurrence of two primary intracranial tumors is a rare event, especially if unrelated to radiotherapy or genetic disorders. We present two patients, both with two primary intracranial tumors simultaneously present at adjacent sites, in order to explore a possible mechanism of synchronous tumor formation. METHODS: We performed a molecular analysis of the K409Q mutation of the KLF4 gene, in addition to conventional immunohistochemistry. RESULTS: Preoperative gadolinium-enhanced magnetic resonance imaging revealed a necrotic mass with an irregular ring-like enhancement adjacent to a frontal meningioma in patient 1, and an infiltrative non-enhancing glial tumor with no evidence of another tumor in patient 2. Postoperative histological examination revealed the presence of two distinct tumors in both cases: secretory meningioma and glioblastoma in patient 1 and secretory meningioma and anaplastic astrocytoma in patient 2. Secretory meningiomas both showed the KLF4 K409Q mutation, while none of the glial tumors had it. CONCLUSIONS: To our knowledge, these are the first two cases reported of the simultaneous occurrence of secretory meningiomas with mutation of KLF4 in collision with a glioblastoma and an anaplastic astrocytoma, respectively. These collision tumors presumably have different molecular origins.