Lalu Prasad 45 yrs old male presents to OPD with complaining the continuous non-progresive headache from last 7 days. He believes that he has brain tumor for that there is he consulting many neurologists in past even all of investigation have been with in normal limits. Pt requested for other investigation to revealed that he has brain tumor. Psychiatric evaluation shows the disease on the background of normal inves-tigation. The most probable diagnosis is?