Struma ovarii with follicular thyroid-type carcinoma and neuroendocrine component: case report

Abstract

Struma ovarii (SO) is a slow-growing ovarian neoplasm with thyroid tissue as its predominant component. It is an uncommon neoplasm, usually asymptomatic with an unknown risk of malignant transformation. Due to difficulties in assessing the rare biological nature and the discrepancies in the reported cases, a consensus on the appropriate treatment has not been definitively reached. A 50-year-old female was subjected to upper gut endoscopy which showed a 30-mm mass located in the gastric antrum, suggestive of mesenchimal tumor. Incidentally, a pelvic CT scan also documented a solid mass in the right adnexa, with morphological characteristics of ovarian neoplasm. The patient underwent gastrectomy, total hysterectomy, bilateral salpingo-oophorectomy with lymph node dissection, and omentectomy. Histology documented the presence of gastric cavernous angioma, and, in the right adnexa, foci of follicular thyroid-type carcinoma arising in SO with a well-differentiated neuroendocrine component.Here we report and discuss the clinical and morphological presentation of follicular thyroid-type carcinoma arising in SO. The neoplasm was discovered incidentally and had a favorable clinical outcome at 1-year follow-up.

Figure 1

CT appearance of gastric and ovarian neoplasms: 30-mm solid mass with minute calcifications located between the anterior wall of corpus and gastric antrum (a, arrow). Pelvic mass of 65×45×60 mm on right adnexa suggestive of mixed cystic-solid ovarian tumor (b).

Figure 2

Histological and immunohistochemical profile of thyroid type carcinoma in SO. The sections show follicular thyroid cells with the mucoid glandular component (H&E), ×10 (a); strong and diffuse CD56 reactivity, ×20 (b); Chromogranin A expression in ovarian struma, showing the neuroendocrine cells × 20 (c); Intrafollicular material and the immunoreactivity for thyroglobulin, ×20 (d).

Figure 3

Histological and immunohistochemical profile of thyroid type carcinoma in SO. Microscopical relationship between SO and ovarian teratoma: on the right side mature bone tissue with osteoblasts; on the left, follicular thyroid cancer cells, ×20 (a). Vascular invasion: capillary structures are invaded by cancer cells in the pericapsular area (b, black arrows). Neuroendocrine tumor morphology with cordonal-alveolar pattern (c). Cavernous hemangioma of the stomach arising from submucosa: on the lower part of the section, normal gastric mucosa and muscolaris mucosae, ×20 (d).