A mass lesion lies in the middle frontal gyrus on the right. It demonstrates a medial peripheral zone of increased signal on T1 without evidence of signal dropout on the T2 weighted scans. There is no real evidence to suggest blood products. No subarachnoid blood. No evidence of central venous thrombosis. Although the lesion is a relatively high signal on the diffusion weighted imaging the ADC shows no decrease, no restricted diffusion. The lesion infiltrates anteriorly into the adjacent anterior frontal gyrus. Little if any surrounding vasogenic oedema. After injection of gadolinium, minor enhancement of the medial and inferior portion of the lesion is suspected. No other contrast enhancing or white matter lesions are identified. No evidence of bony remodelling of the overlying diploic space. MR spectroscopy shows decreased NAA and elevated Choline and mI, suggesting a tumour trace.
Conclusion: Mass lesion of the middle frontal gyrus on the right is likely to represent a low-grade tumour. Differential diagnosis includes DNET, ganglioglioma, circumscribed astrocytoma and/or oligoastrocytoma. The features are not typical of a tumefactive plaque but this is not entirely excluded.