[Characteristic imaging features of primary central nervous system lymphoma in comparison with pathological findings]

To investigate the imaging features of primary central nervous system lymphoma (PCNSL).

The imaging and pathological findings in 13 patients with pathologically confirmed PCNSL were analyzed retrospectively. Of these patients, 5 underwent CT scan, 6 had magnetic resonance imaging (MRI) examination, 1 patient underwent both CT and MRI examinations, and another had both MRI and PET/CT examinations.

Among the 13 patients with PCNSL, 11 were identified to have solitary tumor foci and the other 2 had multiple lesions. Supratentorial tumors were found in 9 patients, infratentorial tumors in 3 patients, and both supratentorial and infratentorial tumors in 1 patient. In 6 cases, the tumor presented isodensity or slight hypodensity on plain CT images, with mild or moderate enhancement after contrast agent injection. The lesions showed isointense or hypointense signals on T1WI and isointense or slightly hypointense signals on T2WI in 7 cases, with obvious homogenous enhancement in 5 cases and microcystic foci in 2 cases after gadolinium injection. Five patients showed the "angular sign" and 4 the "hilar depression sign". All the patients presented with mild or moderate peritumoral edema and space-occupying mass except for 1 patient with diffuse lesions, who showed hypointense signals on T1WI and hyperintense signals on T2WI with obvious nodular enhancement after gadolinium injection and high 18F-FDG uptake on PET/CT. Pathologically, the tumors appeared pinkish or grey-white, soft, with rich blood supply and without capsules. The tumor cells were found to cluster around the blood vessels under microscope.

PCNSL may present with typical imaging features which can be suggestive of the diagnosis. Stereotactic biopsy can be performed when necessary to obtain a definite diagnosis.