Encephalitis-like presentation of methylmalonic acidemia with homocystinuria in a postpartum woman: a case report.

Methylmalonic acidemia with homocystinuria (MMA-HC) is a rare inherited metabolic disorder characterized by diverse and nonspecific clinical manifestations. Here, we report the first case of MMA-HC presenting in the postpartum period, aiming to enhance clinicians' awareness and diagnostic capabilities regarding this condition. This will help prevent misdiagnosis and missed diagnosis, thereby enabling timely and effective treatment for patients. A 17-year-old woman who underwent cesarean section presented with encephalitis-like symptoms shortly after childbirth, including fever, headache, psychiatric disturbances, and limb weakness, accompanied by a progressive macrocytic anemia that worsened significantly from the late prenatal to the early postpartum period, along with markedly elevated red cell distribution width (RDW) and leukopenia and severe hyperhomocysteinemia. Genetic testing confirmed cblC-type MMA-HC. A metabolic crisis was triggered after administering valproate for seizures. The patient was effectively treated with a multidisciplinary approach, highlighting the importance of careful clinical monitoring and systematic metabolic screening in peripartum women presenting with progressive hematological abnormalities and encephalopathic symptoms. It further validates the critical role of early diagnosis and multidisciplinary comprehensive treatment in managing complex inherited metabolic disorders, thereby contributing to enhanced overall diagnostic and therapeutic standards.