Staff Physician Parkview Medical Center Pueblo, Colorado, United States
Introduction : Cervical lymphadenopathy in the setting of thyroid nodules raises high suspicion of metastatic thyroid cancer. However, it is important to keep other differential diagnoses such as lymphoma in mind. We report a case of cervical lymphadenopathy in a patient with Hashimoto's thyroiditis that raised concern for thyroid cancer but was ultimately diagnosed as Hodgkin's lymphoma.
Case Description : A 26 year old lady with Hashimoto's thyroiditis saw endocrinology for thyroid nodules and left sided lymphadenopathy noted on a neck ultrasound done for a 3 year history of a left neck lump, due to concern for thyroid cancer. The patient reported fatigue and intentional weight loss, but no compressive symptoms. On examination, the thyroid was not palpable. The mass was mobile and soft anteriorly, but firm posteriorly. The patient reported a previous benign fine-needle aspiration (FNA) biopsy of this mass but no core biopsies. On ultrasound review, the mass corresponded to enlarged level 3 (3 x 2.15 x 2.1 cm) and level 5 (3.76 x 2.85 x 4.66 cm) lymph nodes, with a hypoechoic core, loss of fatty hilum, internal vascularity, and fine calcifications in the level 5 lymph node. On review of images, the thyroid nodules were actually pseudonodules, therefore patient was advised against a thyroid nodule biopsy. Due to the concerning ultrasound features of lymph nodes, a core biopsy of both lymph nodes was ordered. A diagnosis of classic Hodgkin's lymphoma was confirmed by presence of Reed-Sternberg cells in a background of lymphocytic infiltrate with CD30 and PAX5 staining. The patient is now being treated with ABVD chemotherapy regimen with good response.
Discussion : Hashimoto's thyroiditis is frequently associated with small thyroid nodules. Pseudonodules, an expression of the inflammatory infiltrate, are common in this condition. To the untrained eye, differentiation between true and pseudonodules on ultrasound can be challenging. Our patient had enlarging cervical lymphadenopathy for 3 years without a change in thyroid size but only underwent FNA biopsy due to concerns of thyroid cancer from the presumed true thyroid nodules and lymphadenopathy. The concerning features of fatty hilum loss, hypoechoic core and calcifications in enlarged lymph nodes did not match the appearance of the thyroid pseudonodules, suggesting a different pathology. Metastatic lymph nodes from thyroid cancer tend to have the same features as the malignant thyroid focus. This case highlights the importance of personal review of imaging and consideration of differential diagnoses such as lymphoma for cervical lymphadenopathy, even in the presence of concurrent thyroid disease.
