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Primary sarcomas of the thyroid gland are extremely rare. They have mesenchymal (stromal) features and can resemble undifferen-tiated tumors, rendering differentiation from anaplastic carcinoma difficult. Previous case reports have described sarcomas when in fact these tumors were spindle cell variants of anaplastic carcinoma. This is of little practical significance, as the natural history and response to treatment remain similar. Most malignant thyroid tumors with a sarcoma-like appearance show signs of epithelial differentiation by morphological or immunohistochemical criteria and are therefore classified as undifferentiated tumors. The WHO committee states that diagnosis of thyroid sarcoma should be made only in tumors lacking all evidence of epithelial differentiation and showing definite evidence of specific sarcomatous differentiation [18,19]. Various subtypes have been described including liposarcoma, fibrosarcoma, angiosarcoma, osteo-sarcoma, chondrosarcoma, and leiomyosar-coma [20-23]. Sarcomas may rarely metastasize to the thyroid gland; primary sites other than the thyroid should first be excluded.

Angiosarcoma and hemangioendothelioma are very rare, affecting middle-aged or elderly patients [24]. These tumors are extremely aggressive, resembling the behavior of anaplas-tic cancer. Tumors are typically large with extensive areas of hemorrhage and necrosis (Figure 30.2) [25,26]. Microscopically, endothe-lial differentiation together with immunoreac-

Figure 30.2 A Epithelioid angiosarcoma of thyroid. Massive recurrence in the right supraclavicular fossa extending into the superior mediastinum following total thyroidectomy. B Inoperable tumor threatened exsanguination despite chemotherapy but rapid shrinkage followed EBRT.
Figure 30.3 Thyroid liposarcoma: a large mixed attenuation retrosternal mass compressing the trachea and almost obliterating the lumen of the esophagus.

tivity to factor VIII-related antigen and keratin are common [27]. Cases have been described from the Alpine regions of Central Europe where iodine deficiency is common. An enlarging mass following a long history of goiter, with invasion of local structures and lymph node involvement (unusual with other sarcoma subtypes) is the typical presentation. Hemothorax from pleuropulmonary metastases may occur at presentation [24]. Prognosis is poor, with the majority dying of locoregional or metastatic disease. As with sarcoma at any site, surgery remains the definitive and potentially curative treatment comprising total thyroidectomy with excision of any locally involved tissue, along with neck dissection. This may be impossible in the majority of cases if tumor extends beyond the thyroid capsule and invades vital structures. Postoperative radiotherapy is indicated but the role of chemotherapy is yet to be established.

All other sarcomas are extremely rare, with only a limited number of reports in the literature [20,22,28-35]. We have reported two patients with liposarcoma (Figure 30.3) treated by macroscopic resection and external beam radiotherapy that achieved locoregional control; although one died of pulmonary metastases after 10 months the second remains alive with metastatic disease at 24 months.

Survival in sarcomas of the head and neck is shorter than that of limb sarcomas and local recurrence is more frequent. A series of 130 head and neck sarcomas treated at the Royal Marsden Hospital showed an overall 5-year survival of only 50%. Results with surgery alone were poor, as were those with radiotherapy as sole treatment. However, surgery with radiotherapy improved survival. Radiotherapy is recommended pre- or postoperatively as curative management [36].

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