"Enlargement" indeed seems more appropriate here.

hila is also used

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Note added at 38 mins (2010-08-10 03:06:51 GMT)
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Hilum
depression on the mediastinal surface of the lung where the bronchus, the blood vessels and nerves enter

I don't think you can say a depression is "enlarged" but rather is "increased"

Just so that we know what we're talking about, this is a nice explanation:

"The hilum refers to a collection of structures in the chest. These include lymph nodes, large blood vessels, and major airways. Contrary to the above answer, it is not located at the top of the lung, but actually very close to the heart, at the mid-chest level.

It is important to understand how x-rays work. When an X-ray is done, x-rays penetrate the body part and strike a photographic plate (or detector) on the other side. Dense objects, such as bone, will absorb the x-rays. Air, on the other hand, will allow complete transmission. Soft tissues, such as fat, muscle, fluid, will absorb varying amounts. However, since the x-ray is a 2-dimensional representation of a 3-dimensional object, the resulting film is combination of "shadows."

Therefore, "mild fullness of the left hilum" suggests that there may be enlargment of the hilar structures or a mass in the area. Occasionally, this fullness may be an artifact due to the X-ray technique."

http://answers.yahoo.com/question/index?qid=20080404144320AA...

According to a radiology encyclopedia:

"The dense hilum sign suggests a pathological process at the hilum: hilar malignancy or bronchogenic carcinoma should be suspected.

On a well centred chest PA radiograph the density of the hilum is comparable on both sides. In absence of calcification or adenopathy, the hila should appear of equal density and be symmetric."

http://radiopaedia.org/articles/dense-hilum-sign-2

Synonyms:
bilateral enlarged hilar structures
hilar prominence
presence of hilar infiltrate
hilar lympadenopathy or nodules

A prominent hilar shadow on the chest x-ray of a 21 year old non-smoker suggests sarcoidosis, pulmonary hypertension or lymphoma. Other considerations include tuberculosis or a fungal infection, while lung cancer is an unlikely diagnosis. However, in some cases the isolated x-ray abnormality is not significant for any disease. To evaluate it further, a CT-scan and an electrocardiogram would be needed, and they may suggest the need for a bronchoscopy and a biopsy of any solid lesion. Sputum examination may not be reliable, and blood tests cannot provide a definitive diagnosis. Skin testing for tuberculosis would be significant if the test was positive, provided it was known to be negative previously.
http://doctor.ndtv.com/faq.aspx?fid=3602

I am a 52 year african american. A few days ago I had a chest x-ray as part of a physical examination. I had the chest xray because I tested positive for TB skin
test about 26 years ago. The radiologist report indicated "no significant abnormalities revealed in the heart, lungs, tissues, bones, etc. However, radiologist indicated is a slightly prominent hila. The radiologist recommended comparing with previous Xray (I think the last one was 10 years ago), or I need to be checked to rule out adenopathy. I use to smoke (very light) about 17 years, and I exercise 3-5 times a week.
http://www.medhelp.org/posts/Respiratory-Disorders/Slightly-...
Hilar prominence on the chest radiograph is usually due to vascular engorgement or lymphadenopathy.
Adenopathy or Lymphadenopathy is the abnormal enlargement of lymph nodes (usually associated with disease).
http://answers.yahoo.com/question/index?qid=20090721065658AA...