title: Tracheal carcinoma presenting as a thyroid cyst.
abstract: A patient was seen with a thyroid cyst. Fine- and core-needle biopsies revealed no evidence of tumor. A thyroid cyst lined by malignant squamous cells was found at surgery. Invasive squamous carcinoma was found to arise in adjacent trachea. The thyroid gland was normal except for inflammatory changes. Aspiration biopsies of thyroid cysts may be misleading, especially when hemorrhagic; sclerosis should be performed with caution.
mesh_terms: D002294:Carcinoma, Squamous Cell / Q000473:pathology* / Q000601:surgery; D003560:Cysts / Q000473:pathology*; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007828:Laryngoscopy; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D013959:Thyroid Diseases / Q000473:pathology*; D014057:Tomography, X-Ray Computed; D014134:Tracheal Neoplasms / Q000473:pathology* / Q000601:surgery; D014463:Ultrasonography