Hi Shibu,
I found this online:
"The hila are the areas where the right and left lungs split off from the windpipe, or trachea. Around the hila are many lymph nodes. Lymph nodes play an important function in your immune system. There are many lymph nodes throughout the body, including under your jaw, your neck, armpits, groin, and the hila.
Lymphadenopathy describes the condition when lymph nodes are enlarged. The most common reason for hilar lymphadenopathy is infection, such as pneumonia. Other reasons for enlarged lymph nodes include autoimmune diseases, and malignancies."
I hope this helps. I think it will be good to seek a specialist/ dr. advise. I hope your son will be ok
Kassiopeq