A 13-Year-Old Male Patient Is Brought to the Physician to Obtain

A 13-year-old male patient is brought to the physician to obtain a medical exemption letter for swim class. The patient stopped going to swim class due to "feeling uncomfortable in swim trunks." The patient's mother has a concern about his development since starting puberty about a year ago, she noticed that he recently bought women's underwear and shoes and went out to meet friends wearing makeup.  The mother further reports that her child has had mainly female friends since preschool and never enjoyed playing with "typical boy toys like cars" but instead preferred playing with dolls. The patient appears shy and in a depressed mood. Physical examination shows normal male external genitalia. There is scarce coarse, dark axillary and pubic hair. Upon questioning, the patient says "I am trapped in a male body. It just doesn't feel right to be a boy." Which of the following is the most likely explanation of this patient's behavior?

A) Bisexuality
B) Body dysmorphic disorder
C) Fetishistic disorder
D) Gender dysphoria
E) Transvestic disorder