Radiological Category Neuroradiology Principal Modality 1 MRI Principal

Radiological Category: Neuroradiology Principal Modality (1): MRI Principal Modality (2): None Case Report #0452 Submitted by: Supreet Singh, M. D. Faculty reviewer: Clark Sitton, M. D. Date accepted: 30 January 2008

Case History 17 year old African American female with abrupt onset of right sided headache and facial pain, which over a period of one day progressed to diplopia. Evaluation in the ED revealed right lateral rectus muscle palsy.

Radiological Presentations

Radiological Presentations

Test Your Diagnosis Which one of the following is your choice for the appropriate diagnosis? After your selection, go to next page. • Meningioma • Nerve sheath tumor • Lymphoma • Metastasis

Findings and Differentials Findings: There is an enhancing right parasellar mass which is incasing and narrowing the intracavernous component of the right internal carotid artery. There is enhancement of the precavernous segment of the right fifth cranial nerve. The ipsilateral sella or the pituitary stalk do not appear to be involved. CT evaluation of the skull base, and specifically the parasellar region, revealed no lytic destruction of hyperostotic changes in the bones. The involvement of the 5 th cranial nerve and the likely involvement/impingment of the 6 th cranial nerve in the cavernous sinus accounted for the patients symptoms, specifically the facial pain and the lateral rectus palsy. Differentials: • Meningioma • Nerve Sheath tumor • Metastasis • Pituitary adenoma

Diagnosis Primary CNS lymphoma (Precursor T-lymphoblastic lymphoma).

Discussion The appearance of an enhancing right parasellar mass, with encasement and narrowing of the intracavernous carotid artery, is classic, if not pathognomonic, for an en plaque meningioma. The differential diagnosis of the parasellar masses includes schwannoma, pituitary adenoma and metastatsis. In the case, the absense of pituitary involvement made adenoma less likely. Metastatic disease was also unlikely given her young age. Although meningioma remained the most likely diagnosis, the rapidity of symptom onset and the young age of the patient raised sufficient doubt, and a biopsy was performed. The biopsy was consistent with a precursor T lymphoblastic lymphoma. Subsequent whole body PET did not reveal any other sites of disease. Primary CNS lymphoma is a rare entity, especially within a young immunocompetent population. The mean age of primary CNS lymphoma in an immunocompetent population is 60 -70 years. It constitutes 1% and 3% of primary CNS malignancies in the immunocompetent and AIDS patients, respectively. However, for unknown reasons the incidence of primary CNS lymphoma in the immunocompitent people has been rising the US and UK since the early 1980 s.

References 1. Kaufmann, T, Lopez, B, Laws. E et. al. Primary Sellar Lymphoma: Radiologic and Patholgogic Findings in Two Patients; American Journal of Neuroradiology, 23: 364 -367, March 2002. 2. Fitzpatrick, M, Tartaglino, L, Hollander, M, Imaging of Sellar and Parasellar Pathology, Radiologic Clinics of North America, 37: 1, 101 -121. 3. Singh, S, Cherian Rs, George, B, Unusual extra-axial central nervous system involvement of non-Hodgkin’s Lymphoma: Magnetic Resonance Imaging, Australasian Radiology, 44: 1, 112 -114.