welcome to Health care magic.
1.
Lymph nodal enlargement is seen in any infections / inflammations, any underlying medical conditions, malignancies and lymph node malignancy itself.
2.Since he have the familial risk, better to get evaluated as soon as possible.
3.If you are my patient i would have ask for a
ultrasound lymph nodes masses in axillary region, neck, inguinal and abdominal area for enlarged. after that an FNAC to confirm the nature of the node.
4.After that plan for the treatment according to the findings.
5.If it is only one side that to one side, looks like some benign cause.
Hope it helps you. Wish you a good health.
Anything to ask ? do not hesitate. Thank you.