Seronegative autoimmune encephalitis associated with ovarian teratoma and uterine STUMP tumour.

This case report details a case of probable seronegative autoimmune encephalitis (AE) secondary to either an ovarian teratoma or a uterine smooth muscle tumour of uncertain malignant potential (STUMP). AE is a neurological disorder often associated with specific autoantibodies. However, cases can occur without identifiable antibodies, necessitating a broader diagnostic approach. We present a woman in her 30s who exhibited sudden-onset acute behavioural disturbance and psychiatric symptoms. Initial investigations, including both infective and autoimmune screening, returned negative. Further investigations revealed an adnexal mass and raised ovarian tumour markers. Both an ovarian teratoma and a uterine STUMP were resected. Postoperatively, the patient demonstrated significant clinical improvement, with resolution of neurological symptoms and normalisation of cognitive function.