"Hot cross bun" sign resembling multiple system atrophy in a patient with Machado-Joseph disease.

1Department of Neurology, Ataxia Unit, Universidade Federal de São Paulo, São Paulo SP, Brazil; 2Department of Radiology, Universidade Federal de São Paulo and Delboni Auriemo, Diagnósticos da América, São Paulo SP, Brazil. Correspondence: José Luiz Pedroso; Rua Botucatu 740; 04023-900 São Paulo SP Brazil; E-mail: [email protected] Conflict of interest: There is no conflict of interest to declare. Received 14 October 2012; Received in final form 14 May 2013; Accepted 21 May 2013. references A 59-year-old woman presented with a 9-year history of progressive gait instability. She also had rapid-eye movement (REM) sleep behavior disorder and urinary incontinency. Neurological examination revealed ataxia and nystagmus. Brain magnetic resonance imaging showed the “hot cross bun” sign in the pons, as well as cerebellar and brainstem atrophy. Multiple system atrophy (MSA) was suspected, but family history was remarkable for an autosomal inherited ataxia. Genetic testing was positive for Machado-Joseph disease (MJD), which is the most common autosomal dominant spinocerebellar ataxia. MJD may present with REM sleep behavior disorder and dysautonomia, similar to MSA, but to a lesser extent1–3. The “hot cross bun” sign is rarely found in MJD patients (1.3%), but it is a frequent brain imaging feature in MSA4. In this case, a detailed familial investigation was crucial to guide the diagnosis, as MJD is an autosomal dominant inherited ataxia, and MSA is sporadic.