Cytodiagnosis of mucosa-associated lymphoid tissue lymphoma of thyroid gland: An extremely rare presentation in a young female.

Thyroid lymphoma, a rare tumor, constitutes about 1%–5% of all thyroid malignancies and 1%–2% of all extranodal lymphomas. The thyroid gland contains no native lymphoid tissue and is seen only in various pathological conditions such as primary thyroid lymphoma (PTL). PTL is more common in women than men (3:1 predominance) with a peak incidence in the sixth and seventh decades. Mucosa-associated lymphoid tissue (MALT) lymphoma of thyroid is one of the rare variants. Chronic autoimmune thyroiditis (Hashimoto's disease) has been associated with an increased risk of lymphoma, including MALT lymphoma. Here, we report a case of a 38-year-old female who presented with rapidly progressive swelling on the right side of the neck for previous 3 months. No history suggestive of hypothyroidism or hyperthyroidism was present. Ultrasonography showed enlarged thyroid gland with hypoechoic echotexture and multiple echogenic septations. Fine-needle aspiration cytology revealed features suggestive of MALT lymphoma. The swelling was operated, and subsequent histopathology and immunohistochemistry confirmed the diagnosis. Thereafter, the patient was treated by radiotherapy. However, after 6 months' follow-up, there was a recurrence of the tumor. Then, combination of cyclophosphamide, doxorubicin, vincristine, prednisone regime and rituximab was started, and the patient was free of recurrence at the next 12-month follow-up. Here, we report a very rare case of MALT lymphoma of Thyroid occurring in a young female with no known history of Hashimoto's thyroiditis. The tumor recurred after radiotherapy treatment and was successfully treated with subsequent chemotherapy. [ABSTRACT FROM AUTHOR]