The esophageal hiatus is an opening in the diaphragm that allows the esophagus to pass through into the abdominal cavity.
The distance from this to the aortic arch would vary from patient to patient. The relation of the esophagus to the aortic arch can be seen in this diagram:
http://www.hawaii.edu/medicine/pediatrics/pemxray/v6c19g.jpg
Cancer can present in several ways - so the location and onset of the symptoms may be representative of cancer. Enlarged lymph nodes are also possible.
Normally, under the radiologist's impression (found in the x-ray report), there will be possibilities of the hypodense lesion that the radiologist thinks should be considered.
Followup with your personal physician is essential.
This answer is not intended as and does not substitute for medical advice - the information presented is for patient education only. Please see your personal physician for further evaluation of your individual case.
Kevin, M.D.
http://www.straightfromthedoc.com