Methotrexate-associated lymphoproliferative disorder in the thyroid gland of a patient with chronic thyroiditis

Excerpt

A 59-year-old woman visited our hospital with arthralgia for the past 2 years and was diagnosed with rheumatoid arthritis. Bucillamine was ineffective, but methotrexate (MTX) improved her arthralgia. Six years after the initial visit, she felt swelling in her neck. Ultrasonography at our department showed enlarged right and left lobes of the thyroid gland with hypoechoic areas, linear echogenic septations, echo enhancement behind the lesion (Fig. 1a), and abundant blood flow within the lesion (Fig. 1b). Significant cervical lymphadenopathy was not observed. The results of her blood test were as follows: free T₃ 2.43 pg/mL, free T₄ 1.16 ng/dL, thyroid stimulating hormone (TSH) 5.10 μU/mL, thyroglobulin 119.0 ng/mL (reference value, < 32.7 ng/mL), TSH receptor antibody < 0.8 IU/L (reference value, < 2.0 IU/L), anti-thyroglobulin antibody 15.6 IU/mL (reference value, < 28 IU/mL), anti-thyroid peroxidase antibody 214.0 IU/mL (reference value, < 16 IU/mL), and soluble interleukin-2 receptor 305 U/mL (reference range, 121–613 U/mL). She was diagnosed with chronic thyroiditis. Based on the ultrasound imaging, the complications of chronic thyroiditis, and her age, she was suspected of having primary thyroid lymphoma (PTL). Computed tomography showed no other findings suggesting lymphoma in other body areas. Fine-needle aspiration cytology revealed PTL and core needle biopsy was planned. However, she had a history of using MTX. After discontinuation of MTX, her thyroid gland gradually shrank, and ultrasonography confirmed the reduction of the hypoechoic area and blood flow inside the thyroid gland (Fig. 1c, d). Based on these findings, she was diagnosed with methotrexate-associated lymphoproliferative disorder (MTX-LPD).

…