Ovarian teratoma (dermoid cyst) and encephalitis: A link to keep on your radar

Although there is little evidence to support this clinical point, most neurologists passionately believe that once the diagnosis of ovarian teratoma–induced encephalitis is made, the teratoma should be urgently removed to help reduce the risk of permanent neurologic injury.

Challenging clinical issues
Resect the cyst or remove the ovary? The surgical approach to resecting the teratoma may either be complete ovarian cystectomy or oophorectomy. It is important to resect the teratoma in its entirety and avoid spilling the cyst contents into the peritoneal cavity. Based on these considerations, in women who have completed childbearing, an oophorectomy is often performed (FIGURE). For young patients, an ovarian cystectomy or oophorectomy are both suitable options.¹²

Intraoperative ultrasound can be helpful in confirming the presence of small teratomas and in guiding the surgeon to the correct location.¹³

Small teratomas. In cases of encephalitis induced by anti-NMDAR antibodies, the inciting ovarian teratoma can be very small, and not initially detected by ultrasonography.^14,15 This creates a clinical challenge as, among women with anti-NMDAR encephalitis, only about half are reported to have ovarian teratomas. However, if microscopic teratomas could precipitate the syndrome, how is the physician to know which women without imaging evidence of a teratoma should have their ovaries surgically explored or removed?

In a case in which an occult teratoma is suspected to be the cause of anti-NMDAR encephalitis, a multidisciplinary team including a neurologist, radiologist, and gynecologist should confer to determine the best course of action. We should minimize the number of cases in which unnecessary oophorectomy is performed in the hope that a teratoma may be the cause of the encephalitis.

Ovarian teratoma but no anti-NMDAR antibodies. Some patients with encephalitis have a teratoma but no detectable anti-NMDAR antibodies. In these patients, teratoma removal may be associated with improvement in the encephalitis; however, the cause of the condition may be another type of anti-neuronal antibody that has yet to be identified.¹⁶ Women with encephalitis and an ovarian teratoma, and no evidence of infectious or toxicologic causes for the encephalitis, should be considered for teratoma removal.

CASE RESOLVED. Cyst resection contributes to recovery
You arrive at the hospital’s ICU, perform a physical examination, review the ultrasound, and confirm that the patient has an adnexal mass consistent with a teratoma. The anesthesiologist on call has agreed to provide an anesthetic.

You quickly search PubMed and discover that there are more than 180 publications reporting a link between encephalitis and ovarian teratoma, but only a small number are in the obstetrics and gynecology literature.

You take the patient to the operating room and resect the teratoma. The neurologist treats the patient with high-dose glucocorticoids. She recovers slowly, but her neurologic condition improves each day. On postoperative day 14 she is discharged home with a few remaining neurologic deficits. The patient and her family are amazed and grateful. 

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