Clinical Characteristics, Treatment, and Outcomes of Peritoneal Strumosis: A Report of Three Cases and Systematic Review.

Benign struma ovarii (SO) has a probability of metastasis named "peritoneal strumosis", which is extremely rare, such that the specific clinical characteristics, treatment options, and survival outcomes remain unclear. We screened three cases of peritoneal strumosis among 229 cases of SO treated in our hospital. Case 1 was a 36-year-old woman with extensive peritoneal seedings at initial presentation. The second one was a 49-year-old with trocar site implant 11 years after laparoscopic adnexectomy. Case 3 was a 45-year-old woman who had an isolated lesion at the anterior surface of the rectum after laparoscopic ovarian cystectomy for SO 14 years ago. These three patients underwent surgery without any adjuvant treatment and remained disease-free after 30 to 68 months. A systematic review was then conducted and another 16 cases were identified. More than half (10/19, 52.6%) of the patients had previous SO-related ovarian surgery. The median interval between prior SO-related surgery and the initial presentation of peritoneal strumosis was 10.0 years; both regional and distant metastasis, even in the liver, lung, and heart, could also be affected. Surgery was the mainstay therapy (18/19, 94.7%), in which six patients (6/19, 31.7%) were treated with total thyroidectomy (TT) followed by radioiodine (RAI) therapy. Postoperative chemotherapy was only applied in one patient, and the last one only received a diagnostic biopsy without further treatment. Recurrence was noted in two patients with a median recurrence-free survival of 12 years, where surgical excision and RAI were then performed. No death occurred after a mean follow-up of 53 months, where 12 patients achieved no evidence of disease and five were alive with the disease. Peritoneal strumosis has unpredictable biological behaviors and the crude incidence is approximately 1.3% in SO. Patients with peritoneal strumosis have excellent survival outcomes, irrespective of different treatment strategies employed. Surgery with personalized RAI should be preferred and long-term close monitoring is recommended.