Gynecomastia, 4 weeks post-op. Hematoma lumps underneath nipples, scar tissue (Photo)

Thanks for posting your photos. I would say that it is early to inject kenalog to reduce the scar tissue. Without having the ability to palpate the scar, I would imagine that the lump underneath your skin likely represent tissue being brought together by sutures as well as normal scar formation. It takes time to improve and most scar tissue eventually resolves such that there is nothing discrete underneath where you had your incision. 

Hey there,Occasionally, post gynaecomastia surgery blood clots may form, smaller blood clots are left as they are but larger one's causes contour deformities and need drainage. In your case I don't see gross difference in contour between the both sides. I would recommend wearing compression garments for another month or so and then reassess. The chest wall larger clot will show clearly as a deformity by itself within 24 hours. Smaller clots tend to get absorbed and lysed by the body without consequences.
Hope this helps.