Papillary Thyroid Microcarcinoma Arising Within a Mature Ovarian Teratoma: Case Report and Review of the Literature

Mature cystic teratoma is the most common kind of ovarian germ cell tumor. Malignant transformation is uncommon, with thyroid cancer rarely found. Papillary thyroid microcarcinoma has rarely been described as associated with ovarian teratomas. We report a case of a 34-year-old woman who presented with abdominal pain and an ovarian mass. After surgery, the patient was diagnosed with a follicular variant papillary thyroid microcarcinoma that arose within a mature cystic ovarian teratoma. Based on the small size of the primary lesion and patient preferences, no further treatment was performed. To our knowledge, this is the third reported case of papillary thyroid microcarcinoma arising within a mature ovarian teratoma without struma ovarii. There is no consensus on the surgical approach and postoperative management of this condition. Whether further therapy with total thyroidectomy and radioiodine ablation may be beneficial is unknown. In conclusion, papillary thyroid microcarcinoma can also arise within mature ovarian teratomas. Although a favorable prognosis is anticipated, there is limited information about its history or prognosis.

Cytopathologic characteristics of the primary strumal carcinoid tumor of the ovary: a case report with emphasis on differential diagnostic considerations

Primary strumal carcinoid tumor of the ovary (SCTO) is an extremely rare entity, though the survival rate is excellent if the disease is confined to one ovary. A case is presented here in which intraoperative squash smears in a 45-year-old woman with a left adnexal mass revealed dispersed or small clusters of neoplastic cells forming loosely cohesive gland-like structures with abundant cytoplasm. The nuclear chromatin was finely granular with a "salt and pepper" appearance and occasional tiny nucleoli. The position of the nucleus presented a vaguely plasmacytoid appearance. Small fragments of thyroidal colloid-like structures were also identified. A cytopathologic diagnosis of a SCTO was suggested. Further evaluation and immunohistochemical studies were conducted on formalin-fixed, paraffin-embedded material. Cords or nests of uniform cells with abundant cytoplasm, and eccentric nuclei with coarse chromatin and occasional colloidal tissue were identified on H&E sections. The tumor cells showed diffuse and strong cytoplasmic staining for chromogranin A, synaptophysin, CD56, and vimentin but were negative for calretinin, α-inhibin or CDX2. The proliferative index with MIB-1 was around 3%. Thyroidal colloid-like structures were immunoreactive for thyroglobulin and TTF-1 stains. The diagnosis of primary SCTO was confirmed based on cytopathologic, histopathological, and immunohistochemical results, and the location of the tumor. Awareness of the cytopathological findings of SCTO can assist in diagnosing this rare entity correctly.

Thyroid-type carcinoma of struma ovarii

Struma ovarii is a monodermal variant of ovarian teratoma. Thyroid-type carcinoma arising in struma ovarii is rare. The most common type is papillary carcinoma, followed by typical follicular carcinoma, and the new entity of follicular carcinoma-highly differentiated follicular carcinoma of ovarian origin; other forms occur rarely. Consensus on the surgical and postoperative treatment of patients with thyroid-type carcinoma arising in struma ovarii has not been reached. Surgical treatment ranges from total abdominal hysterectomy, plus bilateral salpingo-oophorectomy with omentectomy, to conservative surgery, involving unilateral oophorectomy or strumectomy (cystectomy) for fertility preservation. Adjuvant therapy includes external radiotherapy, chemotherapy, thyroidectomy, and radioactive iodine ablation. Thyroid-type carcinomas arising in struma ovarii, especially the newly recognized entity-highly differentiated follicular carcinoma of ovarian origin-have a favorable prognosis.

Thyroid-type solid cell nests in struma ovarii

Solid cell nests (SCNs) of the thyroid are single or multiple foci of solid and/or cystic clusters of squamoid cells (main cells) with a minor proportion of C-cells, found in the normal thyroid. The SCNs have also been reported in the heart as an ultimobranchial heterotopia. Here, the authors describe a case of thyroid-type SCNs associated with struma ovarii. Main cells were positive for simple and stratified epithelial-type cytokeratins, carcinoembryonic antigen, carbohydrate antigen 19.9, p63, bcl-2, and galectin-3. The neuroendocrine cell population was positive for chromogranin A and synaptophysin but negative for calcitonin, suggesting a common ancestor cell capable of dual differentiation toward thyroid follicular cells and hindgut-type endocrine cells. The existence of thyroid-type SCNs in struma ovarii could be easily understood by considering the struma ovarii as a teratoma; at the same time, these findings also support the idea of a close histogenetic link between the main cells of SCNs and thyroid tissue.