Abstract
In the following report we discuss a very rare case of malignant T-cell lymphoma of the thyroid gland that developed in a 70-year-old woman with a past history of hypothyroidism due to chronic thyroiditis. The chief complaint was a rapidly growing neck mass. CT and ultrasonographic examination revealed a diffuse large thyroid gland without a nodule extending up to 13 cm. Although presence of abnormal lymphoid cells in the peripheral blood was not found, the sIL-2 Receptor antibody and thyroglobulin measured as high as 970 U/ml and 600 ng/mL respectively. Fine needle aspiration cytology diagnosed chronic thyroiditis. A preoperative diagnosis of suspicious malignant lymphoma of the thyroid gland accompanied by Hashimoto’s thyroiditis was made, and a right hemithyroidectomy was performed to definite diagnosis. Histological examination revealed diffuse small lymphocytic infiltration in the thyroid gland associated with Hashimoto’s thyroiditis. Immunohistochemical examination showed that the small lymphocytes were positive for T-cell markers with CD3 and CD45RO. The pathological diagnosis was chronic thyroiditis with atypical lymphocytes infiltration. However, Southern blot analysis of tumor specimens revealed only a monoclonal T-cell receptor gene rearrangement. Finally, peripheral T cell lymphoma was diagnosed. Therefore, the left hemithyroidectomy was also performed one month later. No adjuvant therapy was performed due to the tumor stage and its subtype. The patient is well with no recurrence or metastasis 22 months after the surgical removal of the thyroid. As malignant T-cell lymphoma of the thyroid gland with Hashimoto’s thyroiditis was difficult to diagnose, gene rearrangement examination needed to be performed concurrently.
Highlights
Malignant lymphoma of the thyroid gland is uncommon, representing only 2 to 5% of all thyroid malignancies, and is often associated with autoimmune disorders, such as Hashimoto’s thyroiditis [1]
Case report A 70-year-old woman was referred to our clinic, complaining of rapid anterior swelling at the neck
The patient has a past history of hypothyroidism and enlargement 10 years earlier and takes 50 μg levothyroxinesodiumdaily
Summary
Malignant lymphoma of the thyroid gland is uncommon, representing only 2 to 5% of all thyroid malignancies, and is often associated with autoimmune disorders, such as Hashimoto’s thyroiditis [1]. Histological examination revealed diffuse small lymphocytic infiltration in the thyroid gland associated with Hashimoto’s thyroiditis. The atrophic thyroid epithelia showed enlarged and eosinophilic granular cytoplasm with large nuclei, so-called Hürthle cell metaplasia Around these Hürthle cells there were many plasma cells, lymph follicles with germinal centers and a few eosinophils (Figure 3). Immunohistochemical examinations were performed on formalin-fixed, paraffin-embedded specimens, using an autostaining system according to the manufacturer’s protocol From these results, diffusely infiltrated lymphocytes were positive for T-cell markers (CD3 and CD45RO) and positive for B-cell markers (CD20). There was a small population of B-cell lineage, with no dissociation of surface membranous immunoglobulin light chain kappa or lambda These data suggest the polyclonal nature of infiltrated B lymphocytes associated with Hashimoto’s thyroiditis. There was no rearrangement of the TCR-δ chain or IgH
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