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“Hot Cross Bun” Sign in a Patient With Kelch-like Protein 11 Rhombencephalitis

      A 36-year-old man had progressive gait ataxia, diplopia, and hearing loss over 3 years. On examination, he had upper extremity ataxia, truncal ataxia, bradykinesia, and lower extremity spasticity. Brain magnetic resonance imaging revealed a “hot cross bun” sign (Figure). Kelch-like protein 11 (KLHL11) IgG was detected in serum and cerebrospinal fluid.
      • Dubey D.
      • Wilson M.R.
      • Clarkson B.
      • et al.
      Expanded clinical phenotype, oncological associations, and immunopathologic insights of paraneoplastic Kelch-like protein-11 encephalitis [published correction appears in JAMA Neurol. 2020;77(11):1453].
      Positron emission tomography revealed a hypermetabolic mediastinal mass. Subsequent biopsy revealed seminoma. The hot cross bun sign has been described in patients with multiple system atrophy as well as in a patient with KLHL11 encephalitis.
      • Massano J.
      • Costa F.
      • Nadais G.
      Teaching neuroImage: MRI in multiple system atrophy: “hot cross bun” sign and hyperintense rim bordering the putamina.
      ,
      • Ishikawa H.
      • Mandel-Brehm C.
      • Shindo A.
      • et al.
      Long-term MRI changes in a patient with Kelch-like protein 11-associated paraneoplastic neurological syndrome.
      Some KLHL11 rhombencephalitis cases have been misdiagnosed as multiple system atrophy.
      • Dubey D.
      • Wilson M.R.
      • Clarkson B.
      • et al.
      Expanded clinical phenotype, oncological associations, and immunopathologic insights of paraneoplastic Kelch-like protein-11 encephalitis [published correction appears in JAMA Neurol. 2020;77(11):1453].
      This case highlights the importance of considering KLHL11 IgG evaluation in men with progressive brainstem/cerebellar syndrome despite the radiological findings.
      • Dubey D.
      • Wilson M.R.
      • Clarkson B.
      • et al.
      Expanded clinical phenotype, oncological associations, and immunopathologic insights of paraneoplastic Kelch-like protein-11 encephalitis [published correction appears in JAMA Neurol. 2020;77(11):1453].
      Figure thumbnail gr1
      Figure(A) Axial T2-weighted, (B) axial fluid attenuated inversion recovery, and (C) sagittal T1-weighted precontrast images exhibit T2 hyperintensity of middle cerebellar peduncles (panel B, arrows), cruciform T2 hyperintensity in pons (panels A and B, arrowheads), and marked atrophy of the brainstem and cerebellum (panel C, arrows). Two years earlier, the sagittal T1-weighted precontrast image exhibited only mild brainstem and cerebellar atrophy (D, arrows).

      References

        • Dubey D.
        • Wilson M.R.
        • Clarkson B.
        • et al.
        Expanded clinical phenotype, oncological associations, and immunopathologic insights of paraneoplastic Kelch-like protein-11 encephalitis [published correction appears in JAMA Neurol. 2020;77(11):1453].
        JAMA Neurol. 2020; 77: 1420-1429
        • Massano J.
        • Costa F.
        • Nadais G.
        Teaching neuroImage: MRI in multiple system atrophy: “hot cross bun” sign and hyperintense rim bordering the putamina.
        Neurology. 2008; 71: e38
        • Ishikawa H.
        • Mandel-Brehm C.
        • Shindo A.
        • et al.
        Long-term MRI changes in a patient with Kelch-like protein 11-associated paraneoplastic neurological syndrome.
        Eur J Neurol. 2021; 28: 4261-4266