Primary thyroid leiomyosarcoma: a case report and review of the literature.

Primary thyroid leiomyosarcoma (LMS) is an extremely rare tumor. We report a case of a 47-year-old male with a rapidly growing neck mass and disfagia. Preoperative investigations were diagnostic of anaplastic carcinoma. Total thyroidectomy with partial esophagectomy and dissection of right infrahyoid muscles was performed. Through histolological and immunohistochemical evaluations a primary thyroid high-grade LMS was diagnosed. At 2 months of follow-up a local recurrence was detected and consequently the patient was submitted to chemotherapy with partial response. He is still alive 9 months after surgery. Diagnosis of primary thyroid LMS is difficult due to its similarity to other more common thyroid tumors. To date, there is no standard therapy and prognosis is poor.

The diagnostic value for differentiated thyroid carcinoma metastases of thyroglobulin (Tg) measurement in washout fluid from fine-needle aspiration biopsy of neck lymph nodes is maintained in the presence of circulating anti-Tg antibodies.

OBJECTIVE: Serum thyroglobulin (Tg) is the marker of differentiated thyroid carcinoma (DTC) after total thyroidectomy, but its value is limited by the interference of anti-Tg antibodies (TgAb). Detection of Tg in fine-needle aspiration biopsy (Tg-FNAB) washout fluid is used to identify neck DTC recurrences/metastases, but the interference of serum TgAb in this procedure is unknown. PATIENTS AND METHODS: Seventy-three patients (41 after surgery for thyroid cancer and 32 with thyroid nodules) evaluated for suspicious cervical lymph nodes were retrospectively reviewed. Tg was assayed by immunoradiometric assay or chemiluminescent assay in ultrasound-guided FNAB used for cytology. Serum TgAb were detected by passive agglutination or chemiluminescent assay. On the basis of preliminary data obtained in lymphadenitis, Tg-FNAB more than 36 ng/ml and more than 1.7 ng/ml (in the presence or absence of thyroid gland, respectively) was considered as indicative of metastasis. RESULTS: In 51 TgAb-negative patients, Tg-FNAB was positive in 15 (12 with malignant and three with nondiagnostic cytology), all with histologically confirmed DTC metastases. Of the remaining 36 patients with negative Tg-FNAB, 30 had nonsuspicious and six had suspicious cytology. Histology of the latter showed four undifferentiated thyroid cancer metastases and two lymphadenitis. In 22 TgAb-positive patients, Tg-FNAB was positive in 14 (12 with malignant and two with nondiagnostic cytology), all with histologically confirmed DTC metastases. CONCLUSIONS: Clinical performance of Tg-FNAB appears to be not substantially affected by TgAb, and this procedure remains superior to cytology in the identification of DTC neck metastases. However, cytology should always be performed because, irrespective of TgAb, Tg is undetectable in FNAB from undifferentiated metastases.