[Differential Diagnosis of Immune-Mediated Encephalopathies: "Neurological Symptoms of Diffuse Brain Damage": A New Concept].

In recent years, incidence of autoimmune encephalopathies has increased. The diagnosis of the severe form of autoimmune encephalopathy is not difficult; however, milder forms can be misdiagnosed as general encephalopathies. We often treat Hashimoto's encephalopathy, which has diverse clinical symptoms and is often misdiagnosed as a psychosomatic disease. We have found that the neurological findings and symptoms of patients with Hashimoto's encephalopathy are similar to those of psychogenic diseases, such as giveway weakness and atypical sensory disorder. To understand the mechanism underlying these symptoms, we propose a new concept: neurological symptoms of diffuse brain damage. This theory is based on the premise that etiologically, symptoms observed were caused by diffuse, spotty, and shaded brain damage due to autoimmune encephalopathies. We also found similar neurological conditions in patients with anti-ganglionic acetylcholine receptor antibody-related encephalopathy, encephalopathies that developed after injection of the cervical cancer vaccine, and encephalopathies associated with Stiff person syndrome. In conclusion, the clinical features of autoimmune encephalopathy include the "neurological symptoms of diffuse brain damage" as well as the presence of antibodies. We could diagnose autoimmune encephalopathy more easily, using this new diagnostic concept.

Myopathy in a patient with systemic AA amyloidosis possibly induced by psoriasis vulgaris: An autopsy case.

INTRODUCTION: Amyloid myopathy is a rare manifestation of primary systemic amyloid light-chain (AL) amyloidosis, but it has not been reported to occur in secondary amyloid A (AA) amyloidosis. METHODS: We describe a 46-year-old man with psoriasis vulgaris who presented with idiopathic upper and lower limb weakness and was eventually diagnosed with hypertrophic cardiomyopathy. Muscle biopsy findings were compatible with mild inflammatory myopathy. He died of cardiopulmonary arrest, and an autopsy was performed. RESULTS: The autopsy revealed amyloid plaques immunopositive for AA (but not AL or transthyretin) in the perimysial, perivascular, and endomysial regions of the iliopsoas muscle. The final diagnosis was systemic AA amyloidosis with muscle amyloid angiopathy, possibly induced by psoriasis vulgaris. CONCLUSION: This is an extremely rare autopsy case of myopathy in a patient with systemic AA amyloidosis. The reason for the unusually large amount of amyloid deposition in muscle blood vessel walls remains unclear.