Case of isolated extranodal relapse of diffuse large B-cell lymphoma in the thyroid gland after years of complete remission: A rare presentation

Introduction: Extranodal recurrence of lymphoma is a phenomenon occurring most commonly within the gastrointestinal (GI) tract, central nervous system (CNS), and skin. Isolated involvement of the thyroid gland is rare and can be mistaken for other conditions such as an inflammatory process without the proper clinical setting. Case Report: A 64-year-old female patient with a history of lymphoma which was in complete remission for more than a decade presented with a palpable cervical mass. A computed tomography (CT) scan showed a diffusely enlarged thyroid gland without the presence of pathological lymph nodes throughout the body. During the following weeks, the thyroid gland underwent a rapid increase in size causing severe narrowing of the airways which was confirmed by pathology to be due to diffuse large B-cell lymphoma recurrence within the thyroid gland. Conclusion: A thorough understanding of the patient’s clinical history is crucial for accurate diagnosis, even in rare conditions, and helps prevent delayed initiation of appropriate management.