Rare Presentation of Classical Hodgkin Lymphoma in the Thyroid Gland: A Case Report

Background: Primary thyroid lymphoma (PTL) is a rare malignancy accounting for only 2–5% of thyroid cancers and less than 3% of extranodal lymphomas. Most cases are non-Hodgkin lymphomas, particularly diffuse large B-cell lymphoma and mucosa-associated lymphoid tissue lymphoma. Primary Hodgkin lymphoma (HL) of the thyroid is exceptionally uncommon, with very few cases reported worldwide. Diagnosis is often challenging, as clinical and radiological features mimic other thyroid malignancies, and fine-needle aspiration cytology (FNAC) frequently proves inconclusive. Case presentation: We report the case of a 62-year-old woman with no significant past medical history who presented with a progressively enlarging anterior cervical mass of one year duration. Clinical examination revealed a firm, asymmetric goiter with ipsilateral small cervical lymphadenopathy but no compressive symptoms. Ultrasound demonstrated a large hypoechoic mass in the left thyroid lobe (EU-TIRADS 5) and suspicious cervical nodes. Thyroid function tests were normal. FNAC was non-diagnostic, and the patient underwent total thyroidectomy with prophylactic central neck dissection. Histopathology and immunohistochemistry confirmed a classical Hodgkin lymphoma, nodular sclerosis subtype (CD30+, CD15+, weak PAX5+, Ki-67 index 40%). Staging PET-CT revealed no other disease sites, classifying the case as Ann Arbor stage IE. The patient received ABVD chemotherapy, achieving complete metabolic response after two cycles, and remains in remission at 8 months follow-up. Conclusion: Primary Hodgkin lymphoma of the thyroid is an exceptionally rare diagnosis that should be considered in patients with atypical thyroid masses, particularly when cytology is inconclusive. Definitive diagnosis relies on histopathology and immunohistochemistry. While surgery may be required for diagnosis, systemic therapy with ABVD chemotherapy remains the standard treatment, with excellent prognosis when diagnosed at an early stage.