Hot cross bun sign

The "Hot Cross Bun Sign" in Spinocerebellar Ataxia Types 2 and 7-Case Reports and Review of Literature

Background

The "hot cross bun" sign is a cruciform hyperintensity is seen on T2 weighted imaging within the pons. The sign is considered to be pathognomic for Multiple system atrophy type C. The clinical and radiological features of Multiple system atrophy type C overlap with the autosomal dominant inherited ataxias. We present a case series of 3 African patients with genetically proven Spinocerebellar Ataxia presenting with the Hot cross bun sign and a scoping review of similar studies.

Cases

We described the phenotypic and radiological presentation of genetically confirmed SCA-2 in two, and SCA-7 in one patient, with the "hot cross bun" sign.

Literature Review

We performed a scoping review on the Hot Cross Bun Sign.A total of 66 articles were retrieved. We describe the diverse aetiologies of the sign and associated phenotypic and radiological features. We review the Spinocerebellar Ataxias described with a Hot cross bun sign and make comparisons to Multiple System Atrophy Type C [Ref. 1,2].

Conclusions

To our knowledge this is the first description of an African cohort presenting with the Hot Cross Bun Sign. We expand the differential diagnosis of the Hot Cross Bun Sign.

The “hot cross bun sign” in patients with autoimmune cerebellar ataxia: A case report and literature review

Objectives

The “hot cross bun sign” (HCBs) on magnetic resonance imaging (MRI) has been initially considered specific for multiple system atrophy with cerebellar features. However, a number of other conditions have since been described, which may be associated with this imaging sign. We herein describe a patient with anti-Ri and paraneoplastic cerebellar ataxia, and review the association of the HCBs on imaging with various neurological autoimmune conditions.

Methods

We report a 40-year-old woman with anti-Ri-associated paraneoplastic neurological syndrome and breast carcinoma, in whom brain MRI revealed the HCBs late in the disease course. We also reviewed similar cases reported in the literature.

Results

The patient presented with cerebellar ataxia, polyneuropathy, and pyramidal signs. Although brain MRI was initially unremarkable, the HCBs and T2-weighted hyperintensity of the bilateral middle cerebellar peduncles were observed at later follow-up. Anti-Ri was detected in the serum and cerebrospinal fluid. Breast adenocarcinoma was confirmed via an axillary lymph node biopsy. Her symptoms partially resolved after the first corticosteroid pulse. However, subsequent immunotherapy and tumor treatments were ineffective. Four autoimmune cerebellar ataxia cases with the HCBs (two paraneoplastic and two non-paraneoplastic) were identified in the literature.

Discussion

The HCBs can be associated with paraneoplastic and non-paraneoplastic cerebellar ataxia, which may reflect neurodegeneration secondary to autoimmune injury. Thus, the HCBs should not be considered a contraindication for autoimmune cerebellar syndrome.

Multiple system atrophy mimicry in MRI: Watch out for paraneoplastic rhombencephalitis

The hot cross bun (HCB) sign describes cruciform-shaped T2-weighted hyperintensities of pontocerebellar fibers within the pons and is a typical, but not specific imaging hallmark of the cerebellar variant of multiple system atrophy (MSA-C). We report a case of a 51-year-old woman who was first diagnosed with MSA-C based on progressive cerebellar ataxia, the HCB sign and T2-weighted hyperintensities in middle cerebellar peduncles on MRI. However, further diagnostic work-up revealed positive anti-amphiphysin antibodies in blood and cerebrospinal fluid and subsequently breast cancer. This report of a paraneoplastic rhombencephalitis which initially mimicked MSA-C imaging features stresses the importance of considering immune-mediated rhombencephalitis as differential diagnosis in cases of progressive cerebellar ataxia and the HCB sign on T2-weighted MRI, especially in the absence of pontocerebellar atrophy.