Primary Thyroid Marginal Zone Lymphoma Revealed by a Compressive Goitre: A Rare Diagnostic Challenge

Abstract

Background: Primary thyroid lymphoma (PTL) is a rare extranodal lymphoma often associated with chronic autoimmune thyroiditis and may mimic other thyroid neoplasms, predominantly affecting elderly patients. Aim: This report aims to highlight the diagnostic challenges, imaging features, and therapeutic considerations of this uncommon entity. Case Presentation: We report the case of a 69-year-old patient presenting with a progressively enlarging cervical mass associated with compressive symptoms. Cervical ultrasound revealed a suspicious right thyroid nodule, and biopsy demonstrated a lymphoid infiltrate consistent with marginal zone lymphoma. Cross-sectional imaging showed a large infiltrative thyroid mass with regional lymphadenopathy, while FDG PET-CT confirmed localised disease. Thyroid function tests were normal. Following multidisciplinary discussion, a total thyroidectomy was performed. Histopathological and immunohistochemical analyses confirmed a primary thyroid marginal zone lymphoma arising in a background of chronic lymphocytic thyroiditis, with no lymph node involvement Discussion: Primary thyroid marginal zone lymphoma is an indolent disease with non-specific clinical and radiological features, making histological confirmation essential. Imaging plays a key role in staging and excluding disseminated disease. Management remains controversial, and surgery may be justified in selected cases with compressive symptoms or diagnostic uncertainty. Conclusion: Primary thyroid marginal zone lymphoma should be considered in elderly patients with a slowly enlarging goitre, particularly in the setting of autoimmune thyroiditis. A multidisciplinary approach is crucial to ensure accurate diagnosis and optimal management.