Sections show a benign meningeal neoplasm characterized by a transitional architectural pattern. The tumor is composed of proliferating meningothelial cells arranged in prominent syncytial sheets and conspicuous, well-formed concentric cellular whorls. The tumor cells exhibit abundant, pale eosinophilic cytoplasm with ill-defined cell borders and uniform, bland oval nuclei containing delicate, finely dispersed chromatin; focal intranuclear pseudoinclusions are noted. Tumor is seen infiltrating bony spicules of skull bone and invades the underlying brain tissue (Slide C). No evidence of malignancy.
History of right-sided brain tumor resection seven years ago presents with a recurrent and new bilateral frontal lesion—characterized on recent contrast-enhanced MRI as a large (6.5 x 5.3 cm), homogeneously enhancing, extra-axial solid mass in the left frontal region extending into the right lobe with a broad dural attachment and significant mass effect causing a midline shift—status post-surgical excision for suspected recurrent meningioma.
Soft tissue fragments collectively measured 11x9.5x2 cm, the largest measuring 6.5x5x2 cm.
Bilateral frontal mass, excision: