Background Anaplastic thyroid carcinoma is a rare, rapidly progressive, and highly aggressive tumor. It has a global annual incidence of 1–2 per million people. It mostly affects older adults and women. The median survival duration after diagnosis does not exceed 6–8 months. Case presentation A 60-year-old female patient of mixed race (Honduran) presented to the local medical service with dysphonia that had started approximately 2 months earlier, accompanied by orthopnea that had started 1 month earlier. On physical examination, a soft mass was palpated within the anterior neck region; it was approximately 4 cm in diameter, painless, and mobile on swallowing, and had irregular margins. Ultrasound and computed tomography of the neck were performed. Subsequently, fine needle aspiration biopsy was performed. The histological diagnosis was anaplastic thyroid carcinoma (stage IVB). She underwent total thyroidectomy and chemotherapy. She is currently in her fifth year of remission after diagnosis and remains under oncologic surveillance. Discussion Anaplastic thyroid carcinoma demonstrates a lethal behavior. Approximately 18% survive for more than a year after diagnosis, and 0–10% survive for 5 years. Different pretherapeutic prognostic factors may affect survival, including age < 70 years, the absence of distant metastases, and complete local resection. Conclusion Conventional treatment improves the quality of life of the patient, but the results are not encouraging for the medium and long term. Only a few patients manage to exceed the average life expectancy of 3–6 months, despite undergoing the currently available therapeutic regimen.