Hi, thanks for sharing your friend's health concerns with HCM!
Well, tell me the age/build/significant history of him....the size, feel, texture and any pain...
Anyways, I can perceive the significant tension that your friend shares with you while going through your question...
If I were your treating Doctor or the histopathologist for this case of upper arm lump, I would come up with three possibilities, these include:
1. a
lymph node with neoplastic evidence or tuberculosis
2. The second possibility is of a parasitic
cyst 3. The last possibility is of atypical or borderline tumor-like condition
Hope this answers your question. If you have additional questions or follow up questions then please do not hesitate in writing to us. I will be happy to answer your questions.
Wishing your friend good health.