RESUMO
BACKGROUND: Lacking any squamous epithelium, thyroid gland with primary squamous cell carcinoma (PSCC) proves to be an etiopathophysiological quandary. Two major theories do exist, though few cases have been documented to support either. We present a case that supports the "metaplasia" theory, which serves to enhance our understanding of a disease that carries with it a very poor prognosis. CASE PRESENTATION: We present a case of an extremely advanced, primary squamous cell carcinoma of the thyroid with distant metastases in a thirty-six year-old male. Dying of airway compromise seventeen days following his admission, this is the shortest median survival of all documented cases. CONCLUSION: In addition to being the most abbreviated time period between presentation and death of all documented thyroid primary squamous cell carcinomas, we share the fifth case of thyroid PSCC in the setting of lymphocytic thyroiditis. This case should build awareness of the aggressivity of the disease and the lack of established diagnostic criteria.