Yeungnam Univ J Med.  2021 Apr;38(2):169-174. 10.12701/yujm.2021.00941.

High-grade mucoepidermoid carcinoma in the thyroid gland with poor prognosis

• Shin HC

• KMID: 2515194
• DOI: http://doi.org/10.12701/yujm.2021.00941

Abstract

Mucoepidermoid carcinoma (MEC) is the most common malignant neoplasm of the salivary gland, but primary thyroid MEC has rarely been reported and usually has a good prognosis. Herein, I report a case of thyroidal MEC with a poor prognosis in an 82-year-old woman with an anterior neck mass. Ultrasonography and computed tomography revealed a thyroid mass. The patient initially underwent fine-needle aspiration, was diagnosed with malignancy, and underwent a right lobectomy. On gross examination, a 4.0×3.6×2.6 cm-sized ill-defined, unencapsulated, and infiltrative tan to whitish mass with necrosis was identified. Microscopically, epidermoid tumor cell nests or solid sheets were identified. Mucous cells that were positive for periodic acid–Schiff and mucicarmine stains were also identified within epidermoid cell nests. Frequent mitosis and necrosis were observed. Immunohistochemical staining for p40 and p63 was positive, and that for thyroid transcription factor-1 and PAX8 was focally positive. According to the Armed Forces Institute of Pathology grading system for salivary gland MEC, the current case was classified as high-grade MEC. After surgery, the patient suffered from dyspnea due to a remnant neck mass that compressed and obstructed the trachea; therefore, the patient refused further treatment. Thyroidal MECs are considered low-grade with a favorable prognosis, but there are several reported cases of thyroidal MEC with poor prognosis. The current case is a rare presentation of high-grade thyroidal MEC with a poor prognosis.

Keyword

Carcinoma; Mucoepidermoid carcinoma; Prognosis; Thyroid gland

Figure

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  Fig. 1. Radiological findings. (A) A 4.5 cm-sized hypoechoic mass (arrow) on ultrasonography and (B) a hypoechoic mass (arrow) with peripheral enhancement on computed tomography.

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  Fig. 2. Cytological findings. (A) Polygonal-shaped atypical cell clusters with high nuclear-cytoplasmic ratio and prominent nucleoli are seen (Papanicolaou stain, ×400). (B) Scattered single cells with intracytoplasmic vacuole (arrow) are identified (Papanicolaou stain, ×400).

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  Fig. 3. Gross findings. A 4.0×3.6×2.6 cm-sized ill-defined infiltrative tan to whitish mass with necrosis is present.

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  Fig. 4. Histological findings. (A) Large irregular nests or solid sheets of tumor cells surrounded by fibrotic stroma with necrosis are identified (hematoxylin and eosin [H&E] stain, ×100). (B) The epidermoid cells have prominent nucleoli and keratin pearl formation (H&E stain, ×200). (C) Mitoses are frequently identified (H&E stain, ×400). (D) Vacuolated cells are located within epidermoid cells (H&E stain, ×400). (E) Mucicarmine stain highlights intracytoplasmic mucin droplets (mucicarmine stain, ×400).

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  Fig. 5. Immunohistochemical results. The epidermoid cells are diffusely positive for (A) p63 and focally positive for (B) thyroid transcription factor-1 and (C) paired box gene 8 (immunohistochemical stain, x400).

Reference

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