Unusual extra-axial central nervous system involvement of non-Hodgkin's lymphoma: magnetic resonance imaging.

The MR imaging findings in a patient with non-Hodgkin's lymphoma with unusual involvement of the sella, pituitary stalk and left parasellar region are reported here. On the basis of the MR imaging findings, the initial differential diagnosis included invasive pituitary adenoma, a granulomatous lesion and en plaque meningioma. Trans-sphenoidal biopsy of the sellar mass showed chronic inflammatory changes and the patient was initially treated for tuberculosis. Because follow-up imaging showed the lesion to be progressive, a biopsy was done of an enlarged right inguinal lymph node. This revealed non-Hodgkin's lymphoma.