Primary thyroid extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue type in a patient with breast cancer: a case report and review of literature

Background: Breast cancer coexisting with primary thyroid lymphoma is a very rare combination of multiple primary malignant neoplasms. We present an unusual case of primary thyroid extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue type (MALT lymphoma) occurring in a patient with breast cancer. Case presentation: A 76-year-old female was admitted to our hospital with bilateral thyroid nodules, which were detected two years and eight months ago. In May 2006, she underwent modified radical mastectomy for invasive ductal carcinoma of the left breast. The patient was treated with total left thyroid lobectomy, isthmusectomy and subtotal right lobectomy. Histopathological and immunohistochemical (IHC) examination of surgical specimen confirmed the diagnosis of primary thyroid MALT lymphoma. She received chemotherapy and levothyroxine substitution therapy postoperatively. At the time of last follow-up (seven years and ten months after thyroid surgery), she was found to have a good prognosis (there was no recurrence). Conclusion: Clinical awareness of primary thyroid lymphoma in patients with malignant thyroid nodules should be increased. Surgery should be recommended for suspected malignant thyroid nodules in patients with a history of breast cancer. Post-operative histopathological and IHC examination of surgical specimen confirms the diagnosis. Early treatment is associated with a good prognosis.