Conservative Management of Sclerosing Mucoepidermoid Carcinoma with Eosinophilia of the Thyroid Gland: 12 Years Follow-Up after an Atypical Initial Therapy

Objective: Sclerosing Mucoepidermoid Carcinomas (SMEC) are low-grade malignant tumors with both mucinous and squamous differentiation representing less than 1% of thyroid malignancies. SMEC are sometimes associated with Hashimoto´s thyroiditis and eosinophilia and are more common in females. In rare cases, they have showed a more aggressive behavior with local invasion of the surrounding tissues, trachea, esophagus, or lymph nodes. Distant metastasis to lungs, liver, mediastinum, and bone have also been described. SMEC are usually not responsive to Radioactive Iodine Ablation (RAIA). Despite the generally low risk of recurrence or death, total thyroidectomy and neck dissection is the recommended therapy. Methods: We report the case of a 41 year old female with a SMEC of the thyroid. Hemithyroidectomy without lymphadenectomy was performed. Pathology showed a nodule with a maximum diameter of 1.5 centimeters contacting the capsule. Tumor cells expressed TTF-1, CEA and CK7. No expression for thyroglobulin, calcitonin, cromogranin or CK20 was observed. Results: Complete resection of the thyroid was not performed in this case, and the patient was not treated with radioactive iodine postoperatively. After 12 years of follow-up, the patient did not develop residual disease, neither recurrent loco regional nor metastatic disease. Conclusion: Sclerosing mucoepidermoid carcinoma was treated with hemithyroidectomy, no lymphadenectomy was performed. Despite the size of the nodule and the capsular invasion, the patient had a favourable outcome after a twelve year follow-up. This kind of approach should be taken into account in selected patients.