Does malignant hibernoma exist?

The authors present a case of a highly atypical, possibly malignant, hibernoma. It presented as a deep-seated tumor in the retropharynx of a 57-year-old male. A review of possible similar cases is presented. The patient is without recurrence 4 years after complete excision and radiation therapy. The tumor must be differentiated from liposarcoma. The clinical potential must await the accumulation and observation of additional cases.