Primary leptomeningeal lymphoma

Primary leptomeningeal malignant lymphoma (PLML) is a rare variant of Primary central nervous system lymphoma (PCNSL) which is restricted to leptomeninges.

Patients usually present with multifocal symptoms, with evidence of leptomeningeal enhancement and diagnostic CSF analysis. Although treatment is highly variable, patients have a better prognosis than previously reported and a subset may be cured ¹⁾.

The lesions of PLML can often be detected as an abnormal enhancement on the surface of the central nervous system or the ventricle wall on magnetic resonance imaging (MRIs). Cerebrospinal fluid (CSF) evaluation together with such MRI findings provides the definitive diagnosis of PLM.

Symptoms and signs are referable to multiple levels of the central nervous system. The most common are cranial nerve palsies (predominantly abducens and facial nerve), and lumbosacral radiculopathies; Less frequent symptoms include headache, ataxia, and encephalopathy.

MRI findings usually consist of leptomeningeal enhancement in T1WI, being the most common sites of the spinal cord and nerve roots; CSF studies are always abnormal (elevated opening pressure, leukocytosis, elevated protein concentration, and hypoglycorrhachia); A definitive diagnosis can be made by detection of malignant lymphocytes on cytology or flow cytometry. However, serial lumbar punctures may be required as sensitivity is dependent on the proportion of malignant cells in the obtained sample. If the diagnosis is still not possible, a leptomeningeal biopsy may be required.

Carcinomatous meningitis/drop metastases: difficult to differentiate imagenologically PLML from these two entities. Primary tumor defines the diagnosis. CSF cytology may help to disclose diagnosis;

Infectious leptomeningitis: clinical presentation and CSF findings may orientate the causative agent;

Granulomatous meningitis: similar imaging findings after gadolinium administration, but the usually low signal on T2WI.

A 45-year-old female case of PLML in which hydrocephalus with disproportionately large fourth ventricle was observed at presentation with gait instability. Head MRI revealed no abnormal enhancement and CSF cytology was negative, leaving the cause of hydrocephalus undetermined. Endoscopic third ventriculostomy (ETV) was effectively performed for hydrocephalus and her symptoms disappeared. Nearly 2 years later, she was brought to the emergency room due to unconsciousness with the recurrence of hydrocephalus. MRI showed an expanded fourth ventricle and an abnormal enhancement on the ventricular wall. The endoscopic surgery for improving CSF flow was successful and inflammatory change was endoscopically observed on the ventricular wall involving the aqueduct. Pathological diagnosis of the specimen from the ventricular wall proved B-cell lymphoma. Because neither brain parenchymal masses nor systemic tumors were identified, she was diagnosed with PLML and treated with high-dose methotrexate. She was in a stable state 2 years after the diagnosis of PLML ²⁾.

A 47-year-old woman presented with an indolent mass in the right frontal region. The patient's physical examination demonstrated no focal neurological abnormality. A magnetic resonance imaging (MRI) study revealed a mass lesion in the right frontal region. The patient underwent a right frontal craniectomy and removal of the tumor. Histological diagnosis was diffuse large B-cell lymphoma (DLBCL). The patient received chemotherapy with Rituximab, cyclophosphamide, adriamycin, vincristine, and prednisolone (R-CHOP protocol) every 3 weeks for six cycles. The patient was discharged without a neurological deficit and no evidence of tumor recurrence. There was no systemic dissemination of disease 72 months after the surgery. Until the optimal standard management protocol is established, the treatment should be with an individualized multidisciplinary approach, and continued follow-up and clinical surveillance are recommended for every patient ³⁾