Final answer:
A man who believes his cheeks are 'excessively large' and is seeking a face lift, despite no abnormal findings from health professionals, is most likely diagnosed with Body Dysmorphic Disorder (BDD).
Step-by-step explanation:
The middle-aged man seeking a face lift from a plastic surgeon due to his belief that his cheeks are 'excessively large' is most likely suffering from Body Dysmorphic Disorder (BDD). Considering the information provided, he perceives a flaw in his appearance that seems negligible or non-existent to others and to health professionals, which is a hallmark symptom of BDD. This psychological condition involves a preoccupation with imagined or exaggerated defects in one's physical appearance, leading individuals to seek cosmetic procedures.
Somatic symptom disorder involves a focus on physical symptoms that cause distress. Schizophrenia involves a range of symptoms including delusions and hallucinations, whereas conversion disorder involves neurological symptoms without a medical cause, different from this case. Malingering involves faking illness for personal gain, which does not seem to be the case here.