An autopsy case of coexisting spinal and bulbar muscular atrophy and multiple system atrophy

Here, we report an autopsy case of concurrent spinal and bulbar muscular atrophy (SBMA) and multiple system atrophy (MSA). A 55-year-old man presented with weakness, atrophy, and fasciculation of the tongue and the proximal parts of all limbs. The patient gradually developed severe orthostatic hypotension, urinary retention, and cerebellar ataxia; however, no parkinsonism was observed. The patient succumbed to sudden death during sleep. The autopsy revealed widespread and abundant α-synuclein-positive glial cytoplasmic inclusions in the central nervous system, indicative of MSA. Neuronal loss was also observed in the substantia nigra and locus coeruleus. Consequently, the patient was diagnosed with MSA. Additionally, immunostaining for the monoclonal 1C2 antibody revealed positive neurons in the medulla oblongata and spinal cord, supporting the additional diagnosis of SBMA. Genetic analysis revealed an expansion of 41 CAG repeats in the androgen receptor (AR) gene (normal range: 12-38), confirming the diagnosis of SBMA. Altogether, concurrent SBMA and MSA were diagnosed based on the autopsy findings, making this the first reported case of such coexistence in the Japanese and English literature.