An ectopic tonsil in the hypopharynx of an adult: a case report and literature review

Ectopic tonsils refer to tonsillar tissue located outside the Waldeyer's lymphatic ring and represent a rare anatomical variant. The pathogenesis of this entity remains unclear, and whether such ectopic lymphoid tissue retains immunological function has not been well established. We report a case of an adult presenting with an ectopic tonsil concomitant with a thyroid goiter. The patient underwent surgical excision of both lesions. The postoperative histopathological examination with hematoxylin-eosin staining and immunohistochemistry confirmed that the ectopic tissue exhibited characteristic tonsillar architecture and preserved immune function. Although the clinical incidence of ectopic tonsils is low, this entity should be considered in the differential diagnosis of newly identified hypopharyngeal masses. Furthermore, our findings provide evidence that ectopic tonsils may retain functional immunological properties, offering potential implications for future diagnostic, therapeutic, and etiological investigations.