Primary thyroid lymphoma is a rare histological form of thyroid cancer. It often develops on Hashimoto's thyroiditis and affects elderly women. In order to identify the different epidemiological, clinical, biological, imaging, therapeutic and evolutionary aspects, we conducted a retrospective study spread over a period of 20 years, including 13 patients. The mean age was 61.5 years, with a sex ratio F/H of 1.17. The main reason for consultation was cervical swelling, often compressive. The lymphoma was of type B in all cases: seven diffuse large-cell lymphomas, one extra-ganglionic marginal zone B lymphoma of the MALT type and one small-cell lymphoma. According to the Ann Arbor classification, the majority of our patients were at an advanced stage. Seven patients received chemotherapy. Radiation therapy to the cervical region was performed in four patients. Most did not receive surgical treatment. We noted three deaths, persistent disease in nine patients and complete remission in one patient. The latter had a recurrence.