Mixed anaplastic and squamous cell carcinoma originating from a thyroglossal duct cyst

Background: Carcinoma arising from a thyroglossal duct cyst (TGDC) is a uniquely rare, but well described, occurrence. As the majority of these malignancies favor a papillary subtype, the phenomenon of a mixed anaplastic and squamous cell variant has been virtually unobserved. Case: A 63 year-old woman presented with an enlarging submental mass and left-sided otalgia, which was confirmed to be mixed anaplastic and squamous cell carcinoma originating from a TDGC via a CT scan and open biopsy. The mass was treated with radiation and chemotherapy. At 32 months after treatment, the patient demonstrated complete response to therapy with no signs of recurrence or metastasis. Conclusion: Anaplastic carcinoma originating from a TGDC is an exceedingly rare malignancy variant that may respond to treatment consisting of definitive radiation and chemotherapy. The co-presentation of anaplastic carcinoma with a more differentiated cancer is consistent with the suggestion that this poorly-differentiated malignancy may have arisen from a pre-existing cancer of the TGDC.