Immune-Mediated Megaconial Myopathy: A Novel Subtype of Autoimmune Myopathy
Issued Date
2024-11-26
Resource Type
eISSN
1526632X
Scopus ID
2-s2.0-85208165164
Pubmed ID
39475687
Journal Title
Neurology
Volume
103
Issue
10
Rights Holder(s)
SCOPUS
Bibliographic Citation
Neurology Vol.103 No.10 (2024) , e210001
Suggested Citation
Santilli A.R., Ni O., Milone M., Selcen D., Mehrabyan A.C., Seth A., Hsieh C., Raslan W.F., Alkhalifah M.M., Alenezi R.M., Nicolau S., Soontrapa P., Liewluck T. Immune-Mediated Megaconial Myopathy: A Novel Subtype of Autoimmune Myopathy. Neurology Vol.103 No.10 (2024) , e210001. doi:10.1212/WNL.0000000000210001 Retrieved from: https://repository.li.mahidol.ac.th/handle/123456789/101964
Title
Immune-Mediated Megaconial Myopathy: A Novel Subtype of Autoimmune Myopathy
Author's Affiliation
Corresponding Author(s)
Other Contributor(s)
Abstract
OBJECTIVES: To describe a novel subtype of autoimmune myopathy, immune-mediated megaconial myopathy (IMMM), myopathologically characterized by giant mitochondria (megaconia). METHODS: In this case series, we reviewed the Mayo Clinic Muscle Pathology database, between 2018 and 2023, to identify patients with megaconial pathology, subacute progressive weakness, and hyperCKemia, clinically resembling myositis. We recruited 1 patient from another institute, who had similar clinicopathologic features. RESULTS: Five patients were identified. Age at onset of weakness ranged from 19 to 45.5 years. All patients had proximal weakness, elevated creatine kinase levels (1,214 to 5,920 U/L), negative myositis antibodies, necrotizing myopathology, and nonnecrotic myofibers harboring giant mitochondria. Immunohistochemical studies conducted in 4 patients showed sarcolemmal MHC-1 and C5b9 immunoreactivities. Megaconial pathology was considered pathognomonic of congenital muscular dystrophy due to biallelic pathogenic variants in CHKB. Sequencing of CHKB in 4/5 patients was unrevealing. Immunomodulatory therapy improved weakness and hyperCKemia in 4 treated patients. Of interest, all patients had coexisting pancreatic diseases (3 cystic fibrosis-related exocrine pancreatic insufficiency, 1 pancreatic cancer, and 1 pancreatitis). DISCUSSION: In addition to incurable CHKB-congenital muscular dystrophy, giant mitochondria can also occur in this new subtype of treatable autoimmune myopathy, IMMM. The association between IMMM and pancreatic disorders remains to be elucidated.