The perihilar region is the middle of the lungs where the bronchi and blood vessels merge together. A prominence of this area of the lung could be due to vascular congestion as one possibility. It could be associated with some condition that caused the lymph nodes to enlarge. This area is rich in lymph nodes as well. The lymphatic vessels which returns clear to yellowish lymphatic fluid in a low pressure system similar to the blood vessels drains from the periphery of the lung tissue toward the central hilar regions as well.
The changes mentioned on the chest x-ray are vague and could be due to different reasons. It could be that this is normal for you and that you just have large blood vessels (veins and arteries in and out to and from the lungs. It could be due to some reason of increased resistance to flow in the blood return from the lungs to the left side of the heart. Changes could be due to a current or recent pulmonary infection. Certain disease of the lungs such as sarcoidosis causes prominence of the lymph nodes in the lungs. The definition and explanation of the findings would be clarified by a chest CT scan which has more of a three dimensional representation of the lungs and other structures within the chest.
I hope this information helps. Further questions are welcome if you have others. If my answer has been helpful and to your satisfaction then please remember to press the "ACCEPT" button. Thank You and Best Regards,
Anthony Bray MD