Malignant struma ovarii: a case series
Merve Kutahyalioglu, MD1,2, Eiman Y Ibrahim, MD2, Michelle D Williams, MD3, Ramona Dadu, MD2, Mouhammed A Habra, MD2, Mimi Hu, MD2, Camilo Jimenez, MD2, Steven Waguespack, MD2, Anita K Ying, MD2, Paul H Graham, MD4, Naifa L Busaidy, MD2
(1) Division of Diabetes, Endocrinology and Metabolism, Baylor College of Medicine, Houston, TX, (2) Department of Endocrine Neoplasia and Hormonal Disorders, The University of Texas MD Anderson Cancer Center, Houston, TX, (3) Department of Pathology, The University of Texas MD Anderson Cancer Center, Houston, TX, (4) Department of Surgical Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX
Struma ovarii is a variant of ovarian teratomas in which mature thyroid tissue is the predominant component on histologic examination. It is classified into benign which is the majority of cases and malignant (0.3% to 5% of all cases) on the basis of histopathological features. The most common type of malignant struma ovarii (MSO) is papillary thyroid carcinoma. Due to the paucity of literature on this malignancy, most of the diagnostic and therapeutic approaches are based on case reports and case series. Our objective was to evaluate diagnostic and therapeutic characteristics of patients with MSO.
We retrospectively analyzed our tumor registry data for patients with MSO.
Eleven patients were identified in the database from October 2000 to November 2016 (Table 1). The median age at diagnosis was 42 years (25-65) and follow-up duration was approximately 7 years (0.4 to 25). Presentation was secondary to abdominal pain (n=3), hip pain from pathologic fracture (n=1), dyspnea from pleural effusion (n=1), and incidental discovery/asymptomatic (n=6). Initial surgery included unilateral salpingo-oophorectomy (n=6) or total abdominal hysterectomy with bilateral oophorectomy (n=5). Histopathological review diagnosed six patients with papillary thyroid cancer, four with follicular thyroid cancer, and one with poorly differentiated thyroid cancer. Metastatic disease was detected in five cases; sites included peritoneum, pelvic wall, bladder, liver, lung and bone. Four out of these patients were diagnosed with metastasis at the time of presentation, one patient was noted to have a recurrent bone metastasis one year after diagnosis. Seven of eleven patients underwent thyroidectomy. Two patients were recommended to have thyroidectomy, one opted no surgery and one relocated for care elsewhere. Two patients were not treated due to T1a tumor pathology. Six of seven patients who underwent thyroidectomy received postoperative radioactive iodine (RAI) treatment with median dose of 112 mCi, four of them had RAI-avid metastatic lesions. Three patients received second dose of RAI (median 200 mCi) for recurrent metastatic disease. The one patient who did not receive RAI therapy had negative diagnostic WBS (n=1). Only one patient has received systemic chemotherapy for widely metastatic, KRAS and ERBB2 mutated, poorly differentiated thyroid cancer (Figure 1). All of the patients were alive at the last visit.
Due to its rarity, there is no consensus on the optimal management of MSO. In our series, despite progressive nature of the disease, all patients are alive suggesting overall good prognosis. Further studies are required to determine the optimal treatment approach, especially the role of total thyroidectomy and RAI in low risk of recurrence and non-metastatic MSO patients. Women with MSO should be managed in a multidisciplinary approach coordinated between endocrinologists, gynecological and surgical oncologists.