Carcinoma showing thymus-like element (CASTLE) of thyroid: combined modality treatment in 3 patients with locally advanced disease.

OBJECTIVES: To examine the value of chemotherapy, radiotherapy and surgery for treatment of locally advanced carcinoma showing thymus-like element (CASTLE) of the thyroid. METHODS: Retrospective analysis of 3 Chinese patients in a tertiary referral center in Hong Kong. RESULTS: CASTLE is a rare thyroid malignancy with a frequency of only 0.15% (3/2033 patients) in our center. Three patients (M:F=2:1) aged 43, 49 and 62 years were studied. All 3 patients had advanced T4 disease with extensive tracheal infiltration and airway compression. None had lymph node or distant metastasis. Total thyroidectomy, combined with chemotherapy and radiotherapy, was effective in local control and symptom relief. Etoposide and carboplatin were tried in 2 patients with positive response. Neoadjuvant chemotherapy shrank the tumor rapidly and relieved symptoms of airway compression. All 3 patients had external radiotherapy resulting in good local control. In a patient with inoperable disease, chemotherapy and radiotherapy rendered the disease operable. All 3 patients were symptom-free and alive at 6, 2.5 and 1.8 years after diagnosis. CONCLUSIONS: CASTLE is locally infiltrative and presents at advanced T stage in this small series. Chemotherapy and radiotherapy, apart from surgery, are effective treatment modalities. In cases of inoperable disease or advanced local disease, they can be employed in combination with surgery. Organ preservation of larynx and trachea may be achieved. Chemotherapy can be very useful for rapid relief of symptoms, especially in shrinking tumor to prevent airway obstruction.