Fine needle aspiration cytology of high grade mucoepidermoid carcinoma of the thyroid - A case report

BACKGROUND: Although mucoepidermoid carcinoma is considered a very rare, lo w grade thyroid neoplasm, in two patients ts a very rapid and aggressive ou tcome occurred. We describe the cytologic, histologic and immunohistochemic al findings of a high grade mucoepidermoid carcinoma that evolved into an a naplastic carcinoma. CASE: A 57-year-old man was admitted with dysphagia, dysphonia and odynopha gia. The patient had begun to develop symptoms over the previous two months . Ultra sound and computed tomography revealed diffuse en largement of the thyroid gland with multiple, bilateral, palpable lymph nodes in the cervica l, supraclavicular, paratracheal and retrocaval chains. The patient died fo ur weeks after receiving the first cycle of treatment with adriamycin and c isplatin. The smears were highly cellular, with a background rich ill neutr ophilic, inflammatory infiltrate and necrotic debris. Two main types of tum or cell were identified: squamoid and mucus secreting. Squamoid cells were polygonal, with well-defined borders and dense cytoplasm. Nuclei varied gre atly in shape and size and displayed clumped chromatin and prominent nucleo li. Mucus-secreting cells were ring shaped and dispersed among the squamoid cells; they contained a large vacuole, with condensed acid and neutral muc ins, that peripherally displaced the nucleus. Small and large clusters of l arge, polygonal cells with single or multiple bizarre nuclei and less-dense cytoplasm were also present. Histology re revealed tumor cells distributed in irregular nests, with necrosis surrounded by a fibrous stroma. The pred ominant cells were squamoid, but dispersed mucus-secreting cells were frequ ently seen in the better-differentiated areas. Sparse anaplastic spindle ce lls were observed adjacent to the squamoid focus. Immunohistochemistry reve aled a reaction positive for cytokeratin (AE3/AE1) in tumor nests and negat ive staining for thyroglobulin and neuroendocrine markers. CONCLUSION: Although mucoepidermoid carcinoma of the thyroid is a very rare neoplasm, its peculiar cytomorphologic features in fine needle aspiration cytology may contribute to its connect diagnosis.