A case of progressive multifocal leukoencephalopathy presenting white matter MRI lesions extending over the cerebral cortex and a marked decrease in cerebral blood flow on SPECT, and associated with HTLV-I infection

We report a 47-year-old woman with progressive multifocal leukoencephalopathy (PML). She was a carrier of HTLV-I virus, and developed subacute right hemiparesis and marked motor aphasia. She had a malignant lymphoma in the left neck and basal cell carcinoma in the right inguinal region. Three months after the onset, she became unable to walk because of the right leg weakness or to speak because of motor aphasia. Magnetic resonance imaging (MRI) revealed multifocal T2-high lesions in the white matter of the left frontal lobe, and a brain biopsy revealed demyelinating pathology. A biopsy of the left parotid gland revealed a diffuse pleomorphic type large B cell lymphoma. Although anti-HTLV-I antibody was positive in the serum and cerebrospinal fluid (CSF), no adult T-cell leukemia (ATL) cells were found in the blood or CSF. The patient was then admitted to our hospital. Neurological examinations revealed severe motor aphasia, mild sensory aphasia/cognitive impairment, right hemiplegia, mild right hemihypesthesia, limb-kinetic apraxia in the left hand, idiomotor apraxia, agraphia, perseveration, marked spasticity and brisk tendon reflex in four extremities, and positive bilateral pathological reflexes. MRI showed multifocal T2-high lesions mainly in the cerebral white matter, predominantly in the left hemisphere, and partly in the cerebral cortex. No gadolinium enhancement was found. In addition, 99mTcECD-SPECT showed a broad decrease in cerebral blood flow (CBF) in the cortex. Anti-HTLV-I antibody was positive but anti-HIV antibody was negative in serum. ATL cells were found in 1-3% of the peripheral white blood cells after admission. CSF examination revealed that the cell count (1/μl), protein level (24mg/dl), and IgG index (0.4) were all normal. However, the myelin basic protein level (321pg/ml; normal<102) was increased, JC virus DNA was detected by PCR, and anti-HTLV-I antibody (×8) was detected in CSF. The regulatory region of the JC virus DNA in the CSF was partly deleted; immunostaining with anti-JC virus protein antibodies revealed the existence of JC virus in biopsied brain specimens, and these findings were consistent with PML. Her symptoms such as motor aphasia, cognitive dysfunction and left hemiparesis were subacutely progressive, and she developed akinetic mutism two weeks after admission. Since the efficacy of cytosine arabinoside for PML has been reported, she was administered 80mg/day of the drug for five days. After treatment, her communication function was mildly improved but the efficacy was transient. Since it has been reported that HTLV-I, as well as HIV, activates the JC virus promoter and its proliferation, the latent infection of HTLV-I in the central nervous system (CNS) in this case might have stimulated the JC virus proliferation, promoting lesion extension over the cerebral cortex. There have been only a few reports of broad decreases in CBF by SPECT in PML patients. Further MRI and SPECT studies on PML patients are therefore necessary to evaluate the significance of HTLV-I in promoting the JC virus infiltration into the CNS.