Strumal Carcinoid Tumor of the Ovary: Report of Rare Occurrence with Review of Literature

The primary ovarian carcinoid tumor is a very rare ovarian tumor, which accounts for approximately 0.5% to 1.7% of all carcinoids and 1% of ovarian cancer. According to its histopathological features, it can be divided into four categories: insular, trabecular, strumal, and mucinous, among which insular carcinoid is common in Western countries. By comparison, the chain-typed and trabecular carcinoid seem to be common in Asian countries. To date, about 150 cases have been reported in the world, and 40% of them are strumal carcinoid tumor of the ovary (SCTO), which is a highly specialized teratoma differentiated from the monomer, and often characterized by the coexistence of thyroid follicular tissue and carcinoid tissue with the neuroendocrine function. Preoperative diagnosis may be difficult due to the very insidious nature of the disease and its multiple imaging manifestations. We reported the case of a 39-year-old woman with a 5-year clinical history. Gynecologic examination and ultrasonic testing revealed an enlarged ovary with a diameter of about 60 mm, accompanied by a hypoechoic area, which was suspected to be a benign teratoma. Ca-125, AFP, free T4, TSH, and other diagnostic indicators were normal. During the laparoscopic oophorocystectomy of the left ovary, a smooth and solid tumor with the size of 6 × 6 × 5 cm was found in the right ovary. During the operation, a mature cystic teratoma containing a struma was frozen, then the oophorocystectomy of the left ovary was performed. According to the Federation International of Gynecology and Obstetrics (FIGO) in 2014, histopathological examination showed a mature teratoma with thyroid carcinoid stage Ic, and Douglas's cystic hygroma cytopathology was negative. One year after the operation, the patient was tumor-free, with Ca-125, FT4, and TSH being within the normal range. Specific diagnostic tools and serological monitoring of malignant tumors of the ovary have low specificity and sensitivity in the diagnosis of this rare malignant tumor of the ovary. Female patients with habitual constipation, chronic abdominal colic, diarrhea, and endocrine dysfunction also need to be alert to this rare malignant tumor of the ovary.