Rheumatoid nodules in the thyroid bed following total thyroidectomy: a case report

INTRODUCTION Rheumatoid nodules occur in 30 percent of patients with active rheumatoid arthritis. Common sites include the buttocks or the extensor surface of the forearm, with one group documenting their presence in the thyrohyoid membrane. To the best of our knowledge, rheumatoid nodules have not been described in the thyroid bed. CASE PRESENTATION We present the case of a 46-year-old Caucasian woman with active rheumatoid arthritis and Hashimoto's thyroiditis who presented with compressive neck symptoms. An ultrasound scan revealed that both lobes of her thyroid were enlarged. The right lobe measured 7.9×3.4×3.3cm and the left 8.3×3.3×3.1cm. A solitary 1.0×0.6×0.8cm nodule was seen in the right lower lobe. Her thyroid-stimulating hormone level was 4.22uU/mL (0.34 to 5.60). A total thyroidectomy was performed due to her symptoms and the possible growth of a nodule when on levothyroxine. A postoperative ultrasound scan showed no remaining thyroid tissue. The pathology revealed several small neoplasms ranging from a well-encapsulated adenoma to highly atypical follicular and papillary Hurthle cell lesions in the setting of Hashimoto's thyroiditis. Low-dose radioactive iodine (33.4mCi) was given. Four months later, our patient complained of a feeling of fullness in her neck. A solid nodule of mixed echogenicity (5.6×3.3×2.3cm) was seen in the right level VI of the neck, and solid tissue of mixed echogenicity (2.9×2.3×1.7cm) on the left. Following repeat surgery, the pathology from the right specimen showed Hashimoto's thyroiditis. The left specimen had areas of granuloma formation with fibrinoid necrosis and palisading histiocytes, consistent with the histology of rheumatoid nodules. No evidence of malignancy was seen. The patient continues to do well and remains disease-free. CONCLUSIONS Rheumatoid nodules have not been reported in the thyroid bed. Their pathogenesis is not clear. Postoperative release of tumor necrosis factor alpha and local vascular damage may have triggered the nodule formation in this case. Rheumatoid nodules must be kept in the differential diagnosis of an enlarging thyroid in the setting of active rheumatoid arthritis. A fine-needle aspiration biopsy may show granuloma formation and be the most cost-effective initial diagnostic step, especially if there is a concern for malignancy. Early identification of these nodules will help decrease morbidity from unnecessary interventions and result in treatment that is both timely and appropriate.