Case 3
A 70-year-old female was found to have incidental enlargement of the thyroid gland on a routine outpatient visit. Thyroid ultrasound showed multiple heterogeneous nodules in the right and left lobes and isthmus. No neck adenopathy was seen. Thyroid function tests were normal (TSH 0.73 mIU/L, free T4 1.25 ng//dL), and the patient was asymptomatic. Fine needle aspiration of the two largest thyroid nodules was done, and pathology showed scattered highly atypical epithelioid cells suspicious for carcinoma. The patient underwent total elective thyroidectomy for a definitive diagnosis. Pathology showed large pleomorphic B-cells in small vascular channels in both thyroid lobes. Cells were positive for CD10, CD5, BCL-6, and partially positive for MUM1. BCL-2 was negative. No primary thyroid malignancy was found. Staging PET/CT and MRI brain were negative for systemic involvement. CSF analysis was deferred given the lack of clinical and radiological evidence of CNS involvement. The patient continues to be monitored off chemotherapy with serial imaging and remains disease-free.