Can someone who is never speaking of himself and present himself as very altruistic be egocentric / narcissistic?
According to the empathy-altruism hypothesis, in some circumstances, people help because they genuinely care about the welfare of the other person and not because of any other personal goal i.e. avoid distress, social norm, Self-affirmation etc.


  The empathy-altruism hypothesis basically states that
  psychological altruism does exist and is evoked by the empathic desire
  to help someone who is suffering. Feelings of empathic concern are
  contrasted with feelings of personal distress, which compel people to
  reduce their own unpleasant emotions. People with empathic concern
  help others in distress even when exposure to the situation could be
  easily avoided, whereas those lacking in empathic concern avoid
  helping unless it is difficult or impossible to avoid exposure to
  another's suffering.


...


  The social exchange theory states that altruism does not exist unless
  benefits to the helper outweigh the costs. C. Daniel Batson disagrees.
  He holds that people help others in need out of genuine concern for
  the well-being of the other person. The key ingredient to helping is
  "empathic concern". According to his 'empathy-altruism hypothesis', if
  you feel empathy towards another person you will help them, regardless
  of what you can gain from it (1991).


There is a lot of debate about the empathy-altruism hypothesis theory, but I tend to agree with it.