Struma Ovarii

Struma ovarii patients, often aged 40 to 60, more frequently present with ovarian, rather than thyroid hyperfunction complaints [1]. Ovarian symptoms include metrorrhagia, abdominal or pelvic pain or palpable abdominal mass that has no specific traits on clinical examination, making diagnosis difficult. All these signs are nonspecific and overlap with those caused by an ovarian malignancy. Abnormal liquid accumulation like ascites [2] (leading to the presence of a positive fluid wave test) and hydrothorax with ascites (leading to crackles on pulmonary auscultation and dyspnea), known as the pseudo-Meigs syndrome may also be encountered. Ascites occurs in 17 to 33% of patients [3] and may spontaneously disappear after tumor excision. Thyroid tumors may also be present [4]. Struma ovarii may be completely asymptomatic [5] and discovered on pelvic imaging studies or surgery performed for other complaints [1]. Hyperthyroidism signs are present in 5 to 8% of patients [6] [7]. Some of the women affected by the condition also have a goiter [8] due to Graves' disease [9].

Struma ovarii diagnosis is aided by blood workup and imaging modalities. Aside from complete blood cell count, the cancer antigen, although non-specific, may sometimes be useful [2]. However, its presence does not necessarily signify struma ovarii is present, as it is elevated in numerous other physiological and pathological instances. Although hyperthyroidism symptoms may be absent, the serum thyroid-stimulating hormone may be low and free thyroxine and/or triiodothyronine levels may be increased. However, they are not commonly ordered if increased thyroid function signs are absent. Also, despite the fact that clinical examination usually does not describe an enlarged thyroid, serum thyroglobulin level may be increased.

In the attempt to characterize the nature of the pelvic tumor, several methods may be applied. Pelvic ultrasound is usually the first study performed and offers limited information. Triple-contrast computed tomography (CT) scan describes the cystic aspect of the pathological mass and evaluates if lymph nodes and neighboring structures are also implicated [10]. Thoracic radiography is used when lung metastasis or hydrothorax are suspected. If pleural effusion is present, a diagnostic puncture may be useful. Fluid is evaluated to rule out adenocarcinoma. The true thyroid glandular nature of the tumor is highlighted by the sodium iodide I-123 uptake of the pelvic tumor.

After excision, strumal tissue is examined in order to determine if it is malignant or benign. Malignancy is suggested by cellular hyperplasia and atypia, increased mitotic activity, and invasion of underlying structures and consists of thyroid carcinoma or stromal carcinoid [11]. However, there seems to be a thin line between malignant and benign cases concerning histology traits, therefore the end result of therapy cannot be predicted by this method [12]. However, carcinoid variant, even if present, is usually not aggressive and cured by surgical excision [11]. Metastasis can be found in the mesentery, brain, liver, bone, contralateral ovary, peritoneum or lungs.

1. Yoo S, Chang K, Lyu M, et al. Clinical characteristics of struma ovarii. J Gynecol Oncol. 2008;19(2):135-138.
2. Mui M, Tam K, Tam F, et al. Coexistence of struma ovarii with marked ascites and elevated CA-125 levels: case report and literature review. Arch Gynecol Obstet. 2009;279(5):753-7.
3. Kim S, Pak K, Lim H, et al. Clinical diversity of struma ovarii. Korean J Obstet Gynecol. 2002;45:748–752.
4. Zalel Y, Seidman DS, Oren M, et al. Sonographic and clinical characteristics of struma ovarii. J Ultrasound Med. 2000;19:857–861.
5. March D, Desai A, Park C, et al. Struma ovarii hyperthyroidism in a postmenopausal women. J Nucl Med. 1998;29:263–265.
6. Kraemer B, Grischke E, Staebler A, et al. Laparoscopic excision of malignant struma ovarii and 1 year follow-up without further treatment. Fertil Steril. 2011;95(6):2124.e9-e12.
7. DeSimone CP, Lele SM, Modesitt SC. Malignant struma ovarii: a case report and analysis of cases reported in the literature with focus on survival and I131 therapy. Gynecol Oncol 2003;89:543.
8. Young R. New and unusual aspects of ovarian germ cell tumors. Am J Surg Pathol. 1993;17:1210.
9. Teale E, Gouldesbrough DR, Peacey SR. Graves' disease and coexisting struma ovarii: struma expression of thyrotropin receptors and the presence of thyrotropin receptor stimulating antibodies. Thyroid. 2006;16:791.
10. Jung S, Kim Y, Lee MW, et al. Struma ovarii: CT findings. Abdom Imaging. 2008;33(6):740-743.
11. Wei S, Baloch Z, LiVolsi V. Pathology of Struma Ovarii: A Report of 96 Cases. Endocr Pathol. 2015;26(4):342-348.
12. Shaco-Levy R, Peng R, Snyder M, et al. Malignant struma ovarii: a blinded study of 86 cases assessing which histologic features correlate with aggressive clinical behavior. Arch Pathol Lab Med. 2012;136(2):172-178.