A thyroid nodule consistent with chronic lymphocytic leukemia

Summary

Primary thyroid lymphomas are uncommon and mostly comprise diffuse large B-cell lymphomas, whereas chronic lymphocytic leukemia (CLL) presenting in the thyroid is extremely rare. We report a case of a previously healthy 46-year-old man who was referred for evaluation of incidental lymphocytosis. He had no B symptoms, lymphadenopathy, or splenomegaly. Flow cytometry was consistent with a diagnosis of B-cell CLL. The patient was classified as Rai stage 0 and followed up without treatment. Nine years later, he developed splenomegaly and an enlarged inguinal lymph node. A routine CT scan revealed a multinodular goiter, while thyroid function tests were normal. Ultrasound showed a well-defined, solid, hypoechoic right thyroid nodule (16 × 25 × 37 mm) with macrocalcifications, categorized as TI-RADS 4. Fine-needle aspiration cytology demonstrated small, monotonous lymphoid cells (Bethesda V), suspicious for CLL. This is a rare example of CLL presenting as a thyroid nodule long after diagnosis and without systemic progression. This case emphasizes the need to consider hematologic malignancy in the differential diagnosis of thyroid nodules, particularly in patients with known CLL.

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