Punctate pattern and Milky Way appearance caused by PML in a patient with AIDS

Progressive multifocal leukoencephalopathy (PML) is an opportunistic infection caused by reactivation of JC virus in the central nervous system and is an important differential diagnosis in patients with subacute focal neurologic deficits. Magnetic resonance imaging (MRI) is the most sensitive tool for detection of early manifestations of the disease1 . Case Report: A 42-year-old woman with a previous diagnosis of HIV infection, without treatment for the last two years, presented with progressive headache, left hemiparesis, hypoesthesia and homonymous hemianopia in the last two months. CD4 cell count was 16 cel/mm3 and viral load of 99.364 copies/mL. Brain MRI revealed multifocal, subcortical and confluent hyperintense T2/FLAIR lesions in the right parietooccipital lobe, crossing the midline by the corpus callosum, with hyperintense peripheral rim on DWI-image and a central hypointense core, without mass effect. On T2-weighted image, typical multiple punctiform hyperintensities formed the Punctate Pattern, which is known as the Milky Way appearance when nearby a larger PML lesion. The final diagnosis was confirmed by the detection of JC virus on cerebrospinal fluid by PCR. Discussion: The punctate pattern is characterized by at least three punctiform (<5mm) hyperintense lesions on T2/FLAIR images, with or without contrast enhancement. It has already been described in PML, neurosarcoidosis, hematologic diseases, CLIPPERS and CNS vasculitis. Recently it was described as a highly specific feature of PML related to natalizumab, even in pre-symptomatic stages. Further studies are required stablish its incidence in patients with PML from other causes2.