Spongy hump on baby’s head

Patient: This is the second go round for this question.I have a friend whose premature grandson was bornwith a soft lump on the side of his head. He is now over a monthold and the lump and softness is still there He seems tobe gaining weight like he should. he is also an alert baby. The concern is what has caused this lump on his head . Will this remain and affect his overall development? Does he need any special diagnoses and testing?