Abstract
INTRODUCTION: Autoimmune encephalitis is a well-characterized complication of gonadal and extragonadal germ cell tumors (GCT), with a known culprit: anti-N-methyl-D-aspartate receptor antibodies. However, reports of autoimmune encephalitis in patients with central nervous system (CNS) GCT are rare. Here, we describe a case of progressive, severe encephalopathy of unknown etiology in a patient with history of pineal germinoma that responded to immunosuppressive therapy. CASE DESCRIPTION: An 18-year old female with history of pineal germinoma presented with a two month history of worsening confusion, short-term memory loss and nocturnal enuresis three months after achieving complete response following chemoradiotherapy. She denied fevers, headaches, ingestions or trauma. While admitted, her level of consciousness acutely deteriorated, necessitating intubation and mechanical ventilation. During this time, her exam was significant for episodic decerebrate posturing with associated dysautonomia. An extensive workup, including infectious, neoplastic and paraneoplastic testing, was nondiagnostic. An autoimmune encephalitis panel sent to a reference laboratory was negative. Electroencephalography was consistent with severe encephalopathy without evidence of seizure activity. She was treated empirically with plasma exchange, intravenous immune globulin and rituximab, demonstrating a striking return to baseline level of consciousness and extinction of dysautonomia. Nine months after rituximab treatment, she developed headaches, dizziness, diplopia and memory loss. She was treated again with rituximab and had full recovery. DISCUSSION: Autoimmune encephalitis is a known complication in cases of gonadal and extragonadal GCT, characterized by confusion, memory deficits and dysautonomia. However, little literature exists regarding this phenomenon in the genetically indistinguishable CNS GCT. Here, we describe the case of a young woman with history of pineal germinoma who presented with severe encephalopathy. Though no specific agent has yet been identified, the resolution of her symptoms after empiric treatment for autoimmune encephalitis suggests that clinicians should be cognizant of this potential complication in patients with CNS GCT.