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Abstract Details

Anti (3-Hydroxy-3-Methylglutaryl-Coenzyme A Reductase Myopathy: A Muscular Dystrophy Mimicker In Pediatric Patient
Neuromuscular and Clinical Neurophysiology (EMG)
P15 - Poster Session 15 (5:30 PM-6:30 PM)
11-007

10 year old female with no past medical history was evaluated due to subacute progressive muscle weakness, myalgias and cramps. Her family history was unremarkable. On examination, she was found with proximal muscle weakness, 3/5 on MMT without fatigability or skin lesions. Routine laboratories showed transaminitis and elevated creatine kinase (>2000u/L), suggestive of a myopathic process (inflammatory versus muscular dystrophy).

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Rheumatologic work up was negative and EMG showed muscle membrane irritability in all muscles tested. A lower extremity MRI showed muscle atrophy with fatty replacement of the gluteus maximus, a pattern characteristic of muscular dystrophy. Left thigh muscle biopsy showed marked fiber type grouping, atrophic and hypertrophic fibers, moderate fibrosis and inflammation also consistent with muscular dystrophy. Decision was made to start treatment with Prednisone. An IVIG trial was also given in an attempt to keep patient ambulatory while myositis panel and muscular dystrophy panel final results were reported. The patient had significant, although short-lived, improvement of muscle weakness after receiving IVIGs. Her clinical response was more suggestive of an autoimmune disease therefore Methotrexate was added to treatment regimen. Finally, LMGD gene sequencing showed variants of uncertain significance and myositis panel was negative. For this reason, anti-HMGCR testing was ordered which was positive (164H). The patient was continued on immunotherapy and serial IVIG treatment and has remained stable without progression of symptoms.

Anti-HMGCR (3-hydroxy-3-methylglutaryl-coenzyme A reductase) myopathy is a rare auto immune mediated necrotizing myopathy that has been associated with statin therapy. It has also been described in pediatric patients and can resemble LGMD. Our case highlights the importance of screening for anti-HMGCR antibodies in children with suspected dystrophy with good response to initial treatment with steroids and IVIGs as early recognition and treatment are important to avoid long term disability in these patients.

Authors/Disclosures
Rocio C. Delgado Diaz, MD (University of Puerto Rico Medical Sciences Campus)
PRESENTER
Dr. Delgado Diaz has nothing to disclose.
Brenda Deliz Roldan No disclosure on file
Alexandra Montalvo Acevedo, MD (University Pediatric Hospital) Dr. Montalvo Acevedo has nothing to disclose.
No disclosure on file