An Unwonted Clinicopathological Subtype of Thyroid Primary Lymphoma

Primary thyroid lymphomas account for less than 5% of all thyroid malignancies and the majority of cases concern non- Hodgkin's lymphoma of B and T-cell origin as well as Hodgkin's lymphoma. Mucosa-associated lymphoid tissue (MALT) lymphoma are a relatively recently described subset of low grade B-cell non-Hodgkin's lymphoma representing between 6 and 27% of the patients with thyroid lymphomas. These cases occur usually in patients with Hashimoto's thyroiditis having a long indolent course and delayed diagnosis, actually benefit from several therapeutic opportunities among them even surgery and a favorable prognostic. Herein we present a 42-year-old female admitted in our unit for a right firm sensitive thyroid swelling, nonhomogeneous on ultrasound images. FNAB showed cellular smears of mixed follicular cells on a background of mature lymphocytes displaying some nuclear atypia and scanty cytoplasm but no definite malignant elements. Intraoperatively, in addition to the "banal" goiter that was found, some subcentimeter cervical lymph nodes were evidenced. Frozen section showed no evidence of malignant or even suspected cellular elements. However a total right lobectomy and lymph node excision was performed. Microscopy revealed a diffuse lymphoproliferative infiltrate in a background of lymphocytic thyroiditis suggesting a diagnosis of B-cell lymphoma of MALT type and the patient was referred to chemotherapy. She was currently under follow-up without recurrences or metastases after two years from surgery.