From the ABC News report on 'Homosexual OCD': Straight Men Who Suspect They Are Gay:

Steven Brodsky, a psychologist who specializes in obsessive-compulsive disorder, says that at any one time he has a "handful" of clients who are straight and suspect that they are gay.

Brodsky, who is the clinical director of his OCD and Panic Center of N.Y. and N.J., said he had one adult patient who was so crippled by obsessive thoughts about being gay that he was unable to live independently and had to move back in with his parents to cope. Brodsky said he determined his patient had OCD associated with homosexuality.

"He had a classic case," said Brodsky. "He had some sort of feeling that he was attracted to other guys."

This patient was straight, according to Brodsky, but he had intrusive thoughts that were not based on any hard reality in his behavior.

These intrusive thoughts can have real-world consequences:

Brodsky said a previous therapist had misdiagnosed his patient as gay, and at the patient's request, sent him off to reparative therapy, a controversial method that has not been proven to be effective and can be harmful....he says health professionals need a better understanding of OCD so patients receive proper treatment for a mental obsession, rather than counseling for a sexual orientation crisis that he says has nothing to do with mental illness. This type of OCD falls under the category of sexual obsessions, according to Jeff Szymanski, a clinical psychologist and executive director of the International OCD Foundation.

Read more here.