Frog In The Throat

Question:  A 67 year old female is referred for a 2 year history of hoarseness.  She notes globus sensation and occasional pain on the left side of her neck.  Laryngoscopy reveals a cystic mass within the laryngeal ventricle.  The mass is biopsied and excised.  The pathologist informs you that abundant mitochondria and metaplasia were seen in the specimen.  What is the diagnosis?  [Answer will be posted with next week's new question]

Answer to last week's question, "Feed Me" (October 24, 2016): 

Refeeding syndrome.