Abstract
Background: Sarcoidosis is occasionally accompanied by hematologic malignancies, including lymphoma, called sarcoidosis-lymphoma syndrome. Although the mechanism underlying the induction of lymphomas is still unknown, understanding the immunological background of sarcoidosis could help explain the possible mechanisms of the induction of lymphomas. Case Presentation: A 52-year-old woman was diagnosed chronic thyroiditis with normal thyroid function. One year later, she underwent a screening chest radiograph and identified bilateral hilar adenopathy and mediastinum lymphadenopathy. Subsequent mediastinoscopy demonstrated sarcoidosis. Because of the lack of clinical symptoms, steroid treatment was not initiated and regular follow-up was performed. One and a half years after the diagnosis of chronic thyroiditis, she presented with rapid swelling of the thyroid gland. FDG-PET/CT showed intense uptake of FDG in the thyroid gland and multiple lymphadenopathy. Fine-needle aspiration (FNA) cytology of the thyroid gland was only suggestive of a lymphoproliferative disorder and did not provide a definitive diagnosis. Partial thyroidectomy was performed, and the pathology indicated diffuse large B-cell lymphoma (DLBCL) such as high-grade transformation of extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue (MALT) lymphoma. The results of an examination of a paraffin block histopathology specimen by fluorescence in-situ hybridization (FISH) detected BCL6 rearrangement (3q27), which is the most common chromosomal abnormality in DLBCL. After the treatment with R-EPOCH (rituximab, etoposide, vincristine, doxorubicin, cyclophosphamide, and prednisone) chemotherapy, the thyroid gland enlargement has improved markedly, while the lymph nodes remained swelling, that suggested lymph node involvements were due to sarcoidosis. Conclusions: Rapid swelling of the thyroid gland in the setting of chronic thyroiditis should raise suspicion for thyroid lymphoma. Furthermore, our present case might suggest that sarcoidosis accelerate the development and high-grade transformation of thyroid lymphoma. To our knowledge, this is the first reported case of sarcoidosis and primary thyroid lymphoma in the same patient.