Lymphocyte-depleted thymic remnants: a potential diagnostic pitfall in the evaluation of central neck dissections

The head and neck region is a frequent site for potentially confusing incidental benign findings not related to the primary pathologic process and having no impact on patient prognosis. Several lesions are thymic in origin. We report 3 cases of lymphocyte-poor thymic remnants identified in central cervical (level VI) lymph node dissections for unrelated benign and malignant pathology. In each, the rests were nearly completely composed of bland epithelial cells with rare admixed lymphocytes. These cells were immunophenotypically similar to thymic epithelial cells, although they differed in the paucity of associated thymic lymphocytes and lack of Hassall corpuscles. Lymphocyte-depleted thymic remnants in the central cervical compartment are not well described in the literature. It is important to be aware of these and other benign inclusions to avoid making incorrect diagnoses of malignancy.