Lipid Storage Myopathy with Ketonuria: A Case of Fatty Acid Oxidation–Related Myopathy and Encephalopathy due to Multiple Acyl-CoA Dehydrogenase Deficiency

Encephalopathy and Myopathy in children of varying ages can be due to variety of causes including Mitochondrial diseases, metabolic diseases like renal tubular acidosis, storage diseases as well as fatty acid oxidation (FAO) disorders. FAO related disorders have variable clinical presentation and manifest in different ages. They may present with hypoglycemia, effort intolerance, multi organ involvement with or without ketonuria. High degree of suspicion and appropriate investigations are mandatory for diagnosis. Here we describe an 11 Year old boy, born to non – consanguineous parents. Presented with exertion induced muscle pain and fatigue of 1year duration, which slowly progressed to severe weakness and vomiting. His reflexes were retained. Therefore metabolic vs inflammatory muscle diseases were considered. Patient had ketonuria with elevated blood levels of medium chain acyl carnitine and long chain acyl carnitine suggestive of MADD. Urine organic acid assessment showed elevated excretion of 2-hydroxyglutarate (2HG), adipate and arabitol. Muscle biopsy showed multiple fine vacuoles on Eosin- hematoxylin stained preparation. Modified Gomori - trichrome stain showed vacuolated fibers with red granular material consistent with ragged red fibers. Oil Red O stains showed vacuolated fibers with ‘oil red O’ positive material suggesting lipid storage. Above combination of features is consistent of MADD. Genetic evaluation is not done due to financial constraint. Patient was started on high dose riboflavin and carnitine, with which the child became near normal. Our patient is a case of MADD presenting as Reye’s syndrome like features and showed excellent response to riboflavin, carnitine, dietary and life style changes. High degree of suspicion is lifesaving.