P-109 Diffuse Large B-Cell Lymphoma of the Thyroid: A Case Report

Abstract Introduction Primary thyroid lymphoma is a rare malignancy, accounting for 1-2% of extranodal lymphomas and 1-5 %of thyroid malignancies. Diffuse large B-cell lymphoma is the most common type of primary thyroid lymphoma, usually presenting with a rapidly enlarging neck mass with cervical lymphadenopathy. Clinical Case A 50-year-old female with an eight-year history of hypothyroidism and regular follow-ups, who was treated with 100 micrograms of levothyroxine daily, presented with a severe TSH suppression in her last follow-up, in response to which, levothyroxine was held for one month. At the subsequent follow-up visit, an unusual thyroid gland enlargement was detected with euthyroid laboratory findings and no complaints of general or hypothyroidism-related symptoms. On examination, enlargement in both thyroid lobes was detected, with no signs of erythema, tenderness, or lymphadenopathy. Neurologic and cardiovascular examination were normal. Ultrasound showed multiple hypoechoic lesions with clear margins in both thyroid lobes. The largest mass was 36mm*23mm*40mm(17cc) on the right lobe. Five other nodules were detected in the left lobe of the thyroid, with the largest diameter of 14mm. Multiple hypoechoic lymph nodes were seen in the left peri-jugular area, the largest one being 13mm*9mm. Table 1 presents the laboratory findings. Patient was advised for ultrasound-guided FNA cytology. The FNA smear was non-diagnostic, and the patient underwent core needle biopsy, which reported lymphoid cells with a high N:C ratio, irregular nuclear membrane, prominent nucleoli, and a scant amount of cytoplasm suggestive of non-Hodgkin lymphoma. For confirmation, IHC was performed, yielding positive results for CD20, CD10, BCL6, and c-myc, with ki-67 of 80%. These results were in favor of diffuse large B-cell lymphoma (DLBCL) germinal center type. Further imaging studies, including a CT scan, assessed the extent of the disease, which revealed an enlarged thyroid with a few hypodense nodules, and several small lymphadenopathies with a maximum short-axis diameter of 11 mm on both sides of the neck (Levels IV-V), with no other remarkable findings. Diagnosed with stage IE of the disease, the patient underwent 8 cycles of chemotherapy with R-CHOP. Follow-up with a PET scan showed no abnormal lymph nodes or lesions, indicating a positive response to chemotherapy. Mild changes in liver density were noted, which were consistent with mild steatosis. Overall, the patient's condition showed improvement, with no significant abnormal findings during follow-up examinations. The patient is now considered disease-free and placed on regular follow-up. Conclusion This case highlights the rare presentation of primary thyroid DLBCL in a patient with a background of hypothyroidism, emphasizing the importance of maintaining a high index of suspicion for thyroid lymphoma and the crucial role of timely treatment in achieving disease-free survival.Figure 1:Ultrasound of the neck showed multiple hypoechoic lesions with flat and clear margins in both lobes of the thyroid. Table 1:Laboratory findings