Anaplastic thyroid carcinoma associated with local abscess

We studied a 71 year old male, presenting a solitary nodule of the thyroid. The patient referred to a rapid and painful enlargement of a cervical mass on the left side of the neck and hoarseness, without fever, compressive or respiratory symptoms. The nodule was painful, hard in consistency, about 4 cm in diameter, on the left lobe of the thyroid without cervical lymph node enlargement. Laboratory tests showed high levels of leukocytes (WG 18000/mm with 87% of neutrophils), increased erythrocyte sedimentation rate (70 mm 1st hour), normal thyroid function tests, positive antithyroid antibodies (1145 U/ml) and negative antimicrosomal antibodies. Thyroid scan confirmed an heterogeneous nodule with areas of necrosis and calcification (4.4×2.7×3.3cm). FNAC: aspiration of 5 cc of yellow material and smears with significant polymorphonuclear infiltration, negative for neoplastic cells, suggesting acute thyroiditis. Bacteriological and viral tests were negative. The patient was treated initially with antibiotics and later left lobectomy was performed. Histological diagnosis showed an undifferentiated thyroid carcinoma (anaplastic) and immunohistochemically there was strong expression of low-molecular-weight keratin but not of high-molecular-weight keratin, thyroglobulin and calcitonin. The patient underwent total thyroidectomy and lymph nodes removal. Tumoral staging was T1NoMo. Local postoperative radiation therapy was applied (cobaltotherapy). After 18 months the patient is assymptomatic, on 1-thyroxine (0.15 mg/day) and without evidence of metastases or tumor recurrence. The first diagnosis of acute thyroiditis/local abscess was based on clinical presentation, laboratory tests and cytology (significant PMN infiltration without neoplastic cells). A local abcess is usually of infectious nature but may be an undifferentiated thyroid carcinoma. This possibility, and the inefficacy of the therapy, determined urgent surgery in this case. In our case, the tumor presented an unusual course, with low agressivity, located only on the left lobe of the thyroid and with a good survival (over one year). Anaplastic thyroid carcinoma is still a controversial tumor in its origin, its biological characteristics, its natural history and its response to therapy. We have to know more about cancer genesis to understand this extremely complex carcinoma.