A Case of Primary Central Nervous System Lymphoma Located at Brain Stem in a Child

Abstract

Primary central nervous system lymphoma (PCNSL) is an extranodal Non-Hodgkin's lymphoma that is confined to the brain, eyes, and/or leptomeninges without evidence of a systemic primary tumor. Although the tumor can affect all age groups, it is rare in childhood; thus, its incidence and prognosis in children have not been well defined and the best treatment strategy remains unclear. A nine-year old presented at our department with complaints of diplopia, dizziness, dysarthria, and right side hemiparesis. Magnetic resonance image suggested a diffuse brain stem glioma with infiltration into the right cerebellar peduncle. The patient was surgically treated by craniotomy and frameless stereotactic-guided biopsy, and unexpectedly, the histopathology of the mass was consistent with diffuse large B cell lymphoma, and immunohistochemical staining revealed positivity for CD20 and CD79a. Accordingly, we performed a staging work-up for systemic lymphoma, but no evidence of lymphoma elsewhere in the body was obtained. In addition, she had a negative serologic finding for human immunodeficient virus, which confirmed the histopathological diagnosis of PCNSL. She was treated by radiosurgery at 12 Gy and subsequent adjuvant combination chemotherapy based on high dose methotrexate. Unfortunately, 10 months after the tissue-based diagnosis, she succumbed due to an acute hydrocephalic crisis.

Keywords: Brain stem; Central nervous system; Lymphoma; Pediatric.

Fig. 1. Preoperative axial (A) and sagittal (B) gadolinium-enhanced T1-weighted magnetic resonance image showing a poorly demarcated heterogeneous enhanced mass in the pons and cerebellar peduncle. There was no mechanical obstruction of the cerebrospinal fluid outflow pathway.

Fig. 2. Positron emission tomography-computed tomography of brain presented two hot uptake foci in the area of gadolinium-enhancement in the previous magnetic resonance image, that is, in the pons and cerebellar peduncle.

Fig. 3. Histopathological microphotographs of non-Hodgkin's lymphoma. Section of biopsy tissue revealing diffuse infiltration of brain parenchyma by large pleomorphic lymphoid cells (A) (hematoxylin and eosin stained; original magnification ×40). Rare mitotic figures were also seen. Tumor cells exhibited strong staining for CD20 (B) and CD79a (C).

Fig. 4. Whole body positron emission tomography/computed tomography failed to detect any lesion elsewhere in the body.

Fig. 5. These follow-up axial (A) and sagittal (B) magnetic resonance images obtained at 3 months after chemotherapy revealed that the gadolinium-enhanced lesion in the brain stem and cerebellar peduncle had disappeared.