Hot cross bun sign in HIV-related progressive multifocal leukoencephalopathy
A 37-year-old lady presented to us with subacute onset progressive ataxia, with tendency to sway toward the left, of 2 month duration. She had significant weight loss, anorexia, and recurrent fevers for 6 months. She was emaciated, had oral candidiasis, and hepatomegaly. Neurological examination revealed left gaze evoked nystagmus, incoordination involving the left extremities, and slurred speech. HIV serology done was positive with a CD4 count of 28/μL. Cerebrospinal fluid study revealed normal opening pressure, mild elevation of protein (65 mg%) with no cells and normal glucose.\nMRI of the brain multiplanar T1, T2, FLAIR, diffusion and postcontrast done on a 1.5 Tesla system (Avanto-SQ Engine, Siemens Medical Systems, Erlanger, Germany) revealed the classical HCB sign in pons. In addition, there were asymmetrical T2 hyperintense lesions involving the left middle and inferior cerebellar peducle extending into left cerebellar hemisphere with atrophy of the same structures []. The left cerebellar hemispheric hyperintensities were partially suppressible on FLAIR and not enhancing on contrast []. Magnetic resonance spectroscopy revealed reduction of N-Acetylaspartic acid peak with mild elevation of choline. Imaging features suggested a possible necrotic demyelinating process asymmetrically, involving the left cerebellar white matter and transverse pontine fibers consistent with PML.