Thyroid Carcinosarcoma

Background. A rare case of diagnosis and treatment of thyroid carcinosarcoma has been presented. Methods and Results. A 58-yearold woman was diagnosed with squamous cell carcinoma of the thyroid. Thyroid gland US and MRI examinations showed tumor mass in the right thyroid lobe extending to the tracheal wall and intratracheal component. The patient underwent right-sided neck dissection (level II-VI) and thyroidectomy with resection of the tracheal rings, cricoid cartilage arch and the lower parts of the thyroid cartilage on the right side. Conclusions. The present case of thyroid carcinosarcoma is of interest because the carcinomatous component is a rare squamous cell thyroid carcinoma. Our clinical case confirms the aggressive character of such rare disease as thyroid carcinosarcoma, showing a high potential for regional and distant metastases.


Introduction
Most thyroid cancers are differentiated cancers. Papillary thyroid carcinoma is the most common type of thyroid cancer accounting for about 80% of all thyroid cancers. Follicular thyroid carcinoma is the second most common type of thyroid cancer (about 10-20%) [1&2]. Medullar thyroid carcinoma comprises 6-8% of all thyroid cancers. Anaplastic thyroid carcinoma, also called undifferentiated thyroid cancer, makes up 2-3% of all thyroid cancers. The incidence of poorly differentiated thyroid carcinoma is 1-6%. Squamous cell thyroid carcinoma accounts for only 0.2-0.7% of all thyroid malignances. This carcinoma is derived from the embryonic remnants such as thyroglossal duct. The incidence of non-epithelial malignancies (lymphoma, sarcoma, teratoma and others) is 1-2%. Most non-epithelial thyroid carcinomas are different types of thyroid lymphomas [2&3]. Epithelial and nonepithelial thyroid carcinomas are rare and clinically aggressive tumors with poor prognosis. Surgery is the standard treatment for these carcinomas. It is often very difficult to perform such surgery due to extensive extra thyroid spread and regional metastasis.
Carcinosarcoma of the thyroid gland is a very rare tumor accounting for only 0.1% of all thyroid malignancies [4]. The exact pathogenesis of thyroid carcinosarcoma is still unknown [5]. Microscopically, carcinosarcomas contain two independent histological malignant components: carcinoma and sarcoma [5&6]. Carcinosarcoma is extremely aggressive tumor with a poor prognosis [4]. It is known to have early metastasis and progression [4,5,7]. To date, 30 cases of thyroid carcinosarcoma have been reported [5]. We report a new case of carcinoma affecting the thyroid gland.

Methods and Results
A 58-year-old women was first seen with thyroid nodule in histopathological results, spread of recurrent tumor, presence of regional and distant metastases, a special treatment was not given.
Symptomatic therapy was recommended.

Discussion
The term "carcinosarcoma" was first used by Rudolf Virchow in 1865 [8]. Carcinosarcomas have been observed in various organs throughout the body including the ovary, uterus, larynx, lungs, prostate, salivary glands, breast, esophagus, liver and other organs [5]. Indeed, this tumor type usually affects visceral organs and is characterized as unusual and uncommon neoplasm that is comprised by an admixture of two components: carcinomatous and sarcomatous [5&9]. Carcinosarcoma components have different histological patterns. Carcinomatous component is more often associated with follicular and papillary cancers [5,6,7,10].
Sarcomatous component usually has the following histotypes: osteosarcoma, fibrosarcoma, undifferentiated sarcoma and chondrosarcoma [4,5,6,7]. In most cases, structural components of carcinosarcoma are in a tumor by isolated areas with the formation of transition zones with interpenetration of the components [9,10].

Conclusion
The present case of thyroid carcinosarcoma is of interest because the carcinomatous component is a rare squamous cell thyroid carcinoma. Biopsy material showed only squamous cell carcinoma. The aggressive tumor growth can be explained by the nature of squamous cell carcinoma. Accurate diagnosis was possible only after studying surgical specimens. Both tumor components have ability to invasive growth. Lymphogenous metastasis is typical for squamous cell carcinoma. In contrast, lymphogenous metastasis of sarcomas rarely occurs in comparison with carcinomas. In our case, lymph node metastases from undifferentiated sarcoma were detected in equal number with lymph node metastases from squamous cell carcinoma. In accordance with previously approved hypothesis, mesenchimal to epithelial transition is one of the key conditions for developing sarcoma metastases [10]. Signs of mesenchimal to epithelial transition are present in the sarcomatous component of thyroid carcinosarcoma. This is evidenced by the expression of cytokeratin, which is detected using AE1/AE3 antibodies. The presence of distant metastases (lung metastases) is typical for sarcomatous component of carcinosarcoma. Our clinical case confirms the aggressive character of such rare disease as thyroid carcinosarcoma showing a high potential for regional and distant metastases. At present, a comparative study of chromosomal abnormalities of carcinomatous and sarcomatous components is considered a promising approach to clarify the exact histogenesis of carcinosarcoma and to assess the treatment options.