SEVERE KWASHIORKOR AND SCURVY SECONDARY TO AVOIDANT/RESTRICTIVE FOOD INTAKE DISORDER (ARFID) IN A CHILD WITH PREVIOUSLY UNDIAGNOSED AUTISM SPECTRUM DISORDER: A CASE REPORT Abstract Background: Avoidant/Restrictive Food Intake Disorder (ARFID) is highly prevalent in children with Autism Spectrum Disorder (ASD). While selective eating is common, Severe Acute Malnutrition (SAM) manifesting as Kwashiorkor in non-famine settings is rare. This report highlights a life-threatening presentation of nutritional deficiency driven solely by behavioral restriction. Case Presentation: A 6-year-old Thai boy presented with generalized edema, desquamating rash for 2 month. History revealed a 1-year duration of extreme food selectivity, consuming only specific brands of rice crackers and refusal of solids, coinciding with developmental regression. Physical examination revealed anasarca, “flaky paint” dermatosis, and perifollicular hemorrhages. Anthropometry showed severe wasting masked by edema. Laboratory investigations confirmed hypoalbuminemia (2.4 g/dL), anemia, and undetectable Vitamin C levels (<0.10 mg/L). Developmental assessment revealed deficits in social communication and restrictive interests, confirming a diagnosis of ASD. The patient was diagnosed with Kwashiorkor, Scurvy, and ARFID. Management involved a multidisciplinary approach including gradual nutritional rehabilitation to prevent refeeding syndrome, vitamin supplementation, and behavioral therapy initiated with lowdose risperidone. The patient showed significant dermatological and physical recovery within 1 month. Conclusion: Severe nutritional complications can arise from undiagnosed neurodevelopmental disorders. Clinicians must maintain a high index of suspicion for ASD and ARFID in children presenting with unexplained malnutrition. Early identification and multidisciplinary management are essential to prevent irreversible developmental sequelae. ASEAN Journal of Psychiatry, Vol. 28 (1) January, 2026; 1-5.