This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Thyroid, Subject name: Surgery
An 80 year old male presents to OPD with c/o rapidly enlarging neck mass and Hoarseness of voice . He gives a history of untreated papillary carcinoma of thyroid . What would be the likely diagnosis? 
Select and explain. 
A. Medullary thyroid cancer, B. Huhle cell carcinoma, C. Papillary thyroid cancer, D. Anaplastic thyroid cancer
D: Anaplastic thyroid cancer
Answer: D: Anaplastic thyroid cancer 
Explanation: Anaplastic carcinoma - Seen in 7th-8th decade -C/F Sudden increase in the size of swelling Severe pain over the swelling Most common route of spread- Direct invasion Evidence of compression of Trachea - Dyspnea Esophagus - Dysphagia Recurrent laryngeal nerve - Hoarseness of voice Most common site of metastasis - Lungs - Investigations IOC for Diagnosis- FNAC - Treatment For resectable tumor - Total thyroidectomy For unresectable tumor - Tracheostomy (lifesaving procedure when tumor is obstructing trachea) - Poor prognosis.