CASE 7785 Published on 07.10.2009

Pineal primary lymphoma mimicking germinoma

Section

Neuroradiology

Case Type

Clinical Cases

Authors

Sbihi L, Chakir N, Bellakhdar MR, Hassani E, Jiddane M.

Patient

24 years, male

Clinical History
Only seven cases of pineal lymphomas have been cited in literature, almost of secondary lymphoma.
We report a new case of primary B-type large cell non Hodgkin lymphoma (NHL) in an immunocompetent 24 year old man, diagnosed by MR-guided stereotactic biopsy and treated successfully by radiotherapy and chemotherapy.
Imaging Findings
A 24 year old man presented with a 4 month history of progressive headache, with morning vomiting and recent visual loss and diplopia. Physical examination revealed left abducens nerve palsy. No superficial lymphadenopathy was noted.
Computed tomography (CT) showed a pineal region process of 3 cm, well delineated, and presenting a spontaneous high density, homogeneous, with a central calcification. Perilesional oedema and mass effect were moderated. The lesion involved the posterior part of the third ventricle, and both thalami (“butterfly sign”). There was an active triventricular hydrocephalous, secondary to mesencephalic aqueduct compression.
On MRI, the lesion was isointense to the grey matter in T1weighted images (WI), quite hyperintense in T2WI with a central asignal area corresponding to the calcification. It showed intense and homogeneaous contrast enhancement (Fig 1).
A ventriculo-peritoneal derivation was performed to resolve symptoms of raised intracranial pressure with good control on CT (Fig 2).
Tumour markers (alphafoeto-protein, beta-human chorionic gonadotrophin and carcino-embryonic antigen) were not found in blood and cerebro-spinal fluid (CSF). CSF cytology was negative.
Arteriography showed a discrete tumoural blush from posterior-medial choroidal arteries and internal cerebral vein displacement (Fig 3).
MR-guided stereotactic biopsy was improved. Histopathologic diagnosis was large cell non-Hodgkin lymphoma (NHL), marked positively by anti-CD20 and anti-CD23, B-cell markers.
Chest, abdomen and pelvis CT imaging revealed no lesions.
He received chemotherapy (CHOP) followed by cranial radiotherapy with complete remission within 3 years.
Discussion
Common pineal region tumours are germ cell tumours, pineal parenchymal tumours, and less frequently astrocytomas [1]. Only seven cases of pineal NHL were reported in the literature, almost not primary, four without description [2-6]. Our case is a primary pineal lymphoma because there was no other lymphomatous localisation on CT scan initially and after a follow-up of three years.
The prevalence of primary central nervous system (CNS) non-Hodgkin lymphomas (NHL) increased in the last two decades. 90% are located supratentorially, generally in a hemispheric lobe (frontal or parietal) or basal ganglia or periventricular white matter (corpus callosum, capsula) sometimes with a mirror pattern. They are unique in 75% of the cases. Imaging characteristics of CNS lymphomas are hyperattenuated on CT, isointense in T1WI, hypointense on T2WI on MR, well circumscribed with homogeneous intense enhancement and a moderate perilesional oedema. Their aspects are often atypical in immunocompromised individuals. On angiography CNS lymphoma appeared as an avascular mass, or with a subtle arteriolar blush [3].
In pineal region, lymphoma resembles germinoma and pineal parenchymal tumours.
Germ cell tumours affect young ages while lymphoma frequently concerns adults between 50 and 60 years old. Our patient was 24 years old.
Hyperattenuation in CT and hypointensity in T2WI is suggestive of high cellular density.
Calcifications are frequent in all pineal region tumours, particularly germinomas [1]. There was a large central calcification in our case.
Lymphoma is generally a homogenous lesion, while germinoma is more often heterogeneous with microcystic areas [4]. Our lymphoma was homogeneous as in Erdag [3] and Grimoldi [4] cases. In Endo’s report, it was a cystic lesion with nodular enhancement on its roof [2].
Surrounding oedema is generally less marked in lymphoma than other intracranial tumours with low or no mass effect [3]. This item was present in our case.
"Butterfly” extension is usual in lymphoma; but can be found in pineal germinomas and astrocytomas, extending into both thalami.
Ependymal and sub-arachnoidal extension are frequent in CNS lymphomas but can be seen in other PRT (germinoma, high grade astrocytoma, pinealoblastoma, and metastasis). In our case, it was not found by MRI and CSF cytology. Endoscopy could be more effective as in the case of Endo [2].
Tumour markers help in germ cell tumours diagnosis.
Angiography is useful to determine vascular connections before stereotactic biopsy.
Stereotactic biopsy guided by CT or MRI is recommended for histopathologic diagnosis before treatment [1,5]. Some authors prefer endoscopic system for diagnostic biopsy and third ventriculostomy with no complications [2].
The majority of CNS lymphomas are B-type diffuse large cell or immunoblastic NHL.
The suspicion of pineal lymphoma should suggest imaging for all the body to look for other localisations, before biopsy [2].
CNS lymphoma treatment is based on chemotherapy followed by cranial irradiation, with relative poor outcome [2,3,6]. Our patient is on complete remission after three years.
Differential Diagnosis List
Primary pineal B-cell lymphoma
Final Diagnosis
Primary pineal B-cell lymphoma
Case information
URL: https://www.eurorad.org/case/7785
DOI: 10.1594/EURORAD/CASE.7785
ISSN: 1563-4086